Morzan is one of the Forsworn who needs to be developed into an actual character. I like Oblakom's version.
Morzan was a Dragon Rider, the first and last of the Forsworn that served King Galbatorix, as well as the most powerful servant of Galbatorix's before Murtagh. He was the wielder of Zar'roc and the father of Murtagh. In the end of Eldest and through part of Brisingr, he was also supposedly the father of Eragon, but later this is proved false. He became the greatest of all the Broddring Empire's supporters. Although he does not make a physical appearance in the books (having been killed long before the story started), his legacy has a lasting impact on Eragon's quest.
As a Rider
Before his betrayal of the Riders and his service to Galbatorix, Morzan was the idol of Brom. It was said that Morzan belittled him, ordered him around, as well as treated him shamefully, but in spite of this, Brom still reputedly loved him like a brother. It took Morzan's betrayal and his killing Brom's dragon Saphira (Not Eragon's Saphira but a whole different dragon) for him to fall from Brom's favor and truly become his enemy.
However, as Brom later said, Morzan was "strong in body, but weak in mind". The name of Morzan's Dragon is unknown due to the Banishing of the Names or Du Namar Aurboda (a magic spell cast by the dragons to strip the traitorous dragons of the Forsworn of their names done by all of the other dragons that had been bonded to a rider). Because of the red color of his sword, Zar'roc, it is safe to assume that Morzan's dragon was red. Morzan and his dragon eventually betrayed the Order to Galbatorix, becoming the first of the Forsworn.
As a Forsworn
Morzan met Galbatorix, who was at that time a fugitive, under unspecified circumstances. Galbatorix convinced him to leave the door open at Ilirea (now Urû'baen). Why Morzan would grant a request for a notorious enemy of the Riders, or even speak with him, is unknown, but it could suggest hatred, deliberate disobedience, a thirst for domination which he could gain under Galbatorix, contempt for the Riders/elders/elves on Morzan's part, or a former friendship between Galbatorix and Morzan.
Once inside Ilirea, Galbatorix stole a dragon hatchling to replace the dragon he lost. Afterward, Morzan followed him to a place that Riders were loathe to go. Morzan had an obscure teaching there, learning the secrets Galbatorix had gained from a Shade. Several years later, when Galbatorix revealed himself to the world, Morzan stood faithfully by his side. They fought any Rider they met, recruited some into their service, founded the order known as the Forsworn, as well as destroyed the Dragon riders. They then descended on Ilirea and deposed King Angrenost, turning the Broddring Kingdom into the Broddring Empire. Morzan was granted his own castle in the Spine, hidden away from the rest of the world.
Marriage to Selena
Eighty years later, Morzan met a woman named Selena, showed her a small kindness to gain her confidence and later enlisted her as his Black Hand after making her swear oaths in the Ancient Language. After about three years, she became pregnant with his child. Because the other Forsworn might use Selena and the child against him, Morzan hid her in his castle, which he protected using powerful spells: the only other individual to know of Murtagh's existence beside his parents was Galbatorix. Morzan then became the only known one of the Thirteen Forsworn to have a child.
When the child, Murtagh, was born, Morzan kept him and Selena separated, allowing her to visit her son only occasionally. After another three years, when he was in a drunken rage, he threw his sword, hit Murtagh and left him with a large scar on his back. Unknown to Morzan, Brom had infiltrated his castle in his plan to get revenge for the death of his dragon Saphira, only to unintentionally fall in love with Selena. Meeting Brom changed her true name so that Selena was able to break free of her bondage from Morzan and secretly began to supply the Varden, a rebel group Brom had formed to fight the Broddring Empire with information.
Duel with Brom and Death
About fifteen years before the Rider War, Morzan hunted down Hefring and retrieved the stolen dragon egg from him. Shortly after, he came face-to-face with Brom for the first time in several decades. He questioned Brom as to whether he was responsible for the disappearance of his Black Hand. They promptly dueled. Morzan lost and he and His Dragon were killed. Brom then took Morzan's sword, Zar'roc and the egg and then fled.
As the right-hand man to King Galbatorix, Morzan was succeeded by the Shade Durza.
Morzan was tall, with broad shoulders. His hair was as black as a raven's feathers and his eyes were different colors: one blue, one black. He was handsome, but his cruelty and haughtiness were apparent even in his appearance and when he laughed, he always sounded as though he were in pain. Morzan was also missing the tip of one of his fingers. He wore very shiny armor, as if he was deliberately showing everyone who and where he was. It was said by Galbatorix that Murtagh inherited much of Morzan's appearance, while stating, in ignorance, that Eragon had inherited little of his features.
Morzan's full personality before he joined the Forsworn is unknown. However, it was said that Morzan belittled Brom, ordered him around, as well as treated him shamefully, but in spite of this, Brom still reputedly loved him like a brother. This indicates that even then Morzan had a bullying nature. However Brom stated that he was "strong of body but weak of mind" showing that, unlike his strong minded son Murtagh, Morzan was weak willed. He was extremely loyal to Galbatorix and Brom stated that he was by far the most loyal member of the Forsworn. This could be because he didn't possess any sense of morality due to his lack of willpower and only cared about pleasing Galbatorix.
As the first and last of the Forsworn, Morzan was both powerful and cruel. This was evidenced when he threw his sword Zar'roc at his then three-year-old son, Murtagh, in a fit of drunken rage. This might have actually been an accident, but it shows at the very least that Morzan was cruel, careless and irresponsible. Murtagh also stated that he was a cunning man.
Though he was probably fairly intelligent and cunning, he was likely impulsive and impatient. Oromis said he would devise the most cunning of spells, but overlook a crucial detail in the process.
He wore very shiny armor, as if he was deliberately showing everyone who and where he was, indicates an arrogance and narcissism in his character.
His could be considered the most evil dragon-rider pair in history as he was not insane like Galbatorix and was fully conscious of his actions.
Since Morzan has not made a physical appearance in the books, the extent of his powers cannot be certain. It is likely that he was very skilled at swordplay, mental powers and magic, since he was a Dragon Rider and slew many others of the order. He also learned dark magic from Galbatorix and possibly drew power from some Eldunarí he captured during the fall of the riders. Combined with a raging dragon, Morzan was a force to be reckoned with. Paolini stated that Galbatorix eventually gathered most if not all of the Forsworn's Eldunarí for himself, so Morzan's power probably lessened since the Riders' Fall. It is confirmed he was never as powerful as Murtagh became, although before their fight, Galbatorix said that both Eragon and Murtagh were shadows compared to Morzan. It is also stated that he was the most powerful member of the Forsworn despite being human while many were elves. He preferred to fight with a one-handed sword-fighting style, which was the design of his sword, Zar'roc.
Behind the scenes
Children and the Time Gap problem
As revealed in Eldest, it is possible that Eragon may be his son. Also in the synopsis of Eragon at the beginning of Eldest, it says that Eragon is fifteen and that Brom and Jeod stole the egg twenty years ago and killed Morzan in the process, making a five-year gap between his death and Eragon's birth, thus it makes no sense for Morzan to be Eragon's father. However, the same could be said for Murtagh: his "last birthday" as of Eragon was his eighteenth, which would put his birth a year or two after Morzan's death if the "twenty years" number is correct. Thus, if the "twenty years" is not just an estimate or a "rounded up" number of years (like saying "last decade" to mean "seven years ago"), it is impossible for Morzan to have thrown his sword at a three-year-old Murtagh.
In actuality, though, there is no time gap problem. Orik stated clearly in Eldest that Morzan died a decade and a half ago, so he actually died fifteen or sixteen years before the Rider War, thus making it possible for Morzan to be Eragon's father. Also, after Saphira's egg was stolen by Hefring, Morzan was sent to search for it. It is not known how long he was looking before he found Hefring and took back the egg, only to be killed by Brom shortly after. It should be safe to assume that Morzan returned to court periodically to report to Galbatorix, possibly to renew his energy and supplies, as well as to check up on Selena. Therefore, the time frame does work out. However, in Brisingr, it was revealed that Morzan wasn't Eragon's father after all: his father was Brom. Murtagh was led to believe Eragon was Morzan's child and that they were brothers, by the fact they both had the same mother: Selena. But Selena had Murtagh while she was with Morzan and Eragon while she was with Brom.
Cause of death and thievery of Zar'roc
In Brisingr, it is revealed that Brom killed Morzan and His Dragon in a duel, after which he took Saphira's egg and Zar'roc. In the movie adaptation, Brom tells Eragon that Morzan was killed by his own sword (Zar'roc), which Brom had managed to wrest from him. As the movie is separate from the novel, this is not canon. Death by ones own weapon is a common occurrence in fiction, such as in William Shakespeare's Hamlet, so the possibility of Morzan being killed by Brom wielding Zar'roc in a duel is a possibility.
The missing finger
A prominent feature of Morzan's was that he was missing the tip of one of his fingers. The reason for this is unknown. It was most likely cut off during a battle. However, it should be noted that during medieval times, people's hands or fingers were sometimes cut off if they were caught stealing. This could possibly imply that before he became Rider at age ten, Morzan was a thief, who lost a finger for stealing. Such a rough early history would fit in with his later behavior.
Since Galbatorix can be compared to Palpatine from Star Wars, Morzan, as a man close to the king (at least having the right to live in the court), can be compared to Anakin Skywalker/Darth Vader:
Both betrayed many of their own Order (Morzan gave allegiance to Galbatorix and betrayed and murdered his fellow Dragon Riders, while Anakin was corrupted by Palpatine and murdered his fellow Jedi Knights).
Both were proposed at some point to be the father of the main hero (although Morzan wasn't really Eragon's father.)
Both generated children who later turned against their side (Morzan is the father of Murtagh, who turned against the Broddring Empire at least for a few months, while Anakin was the father of Luke and Leia, who turned against the Galactic Empire).
The only two differences are that: while Anakin, redeemed by his son, died to save his son from Palpatine; Morzan died at Brom's hands and that Murtagh quickly returned to the Broddring Empire after only a little while of fighting alongside Eragon.
Personality wise, he more resembles Darth Maul from Star Wars
Both were "strong in body". Both were considered great martial artists and/or physical combatants
Both were extremely loyal to their respective masters (Galbatorix for Morzan, Palpatine for Maul)
Both were considered to possess little to no morality
Both cared about pleasing their masters.
Both were powerful and cruel.
Both were capable of great rage and hate.
Both were intelligent and cunning.
Both were capable of being impatient and/or impulsive.
While both could devise cunning tactics, both were capable of overlooking a crucial detail which undid them.
Both were skilled at swordplay, mental powers and a mystical force (Magic for Morzan, The Force for Maul).
Both slayed members of an opposing order (Morzan slayed fellow Dragon Riders, Maul slayed several Jedi and other force-sensitive users of various factions).
Both were trained in the Dark Arts of the mystic force they utilized by their respective masters.
Both had preferred fighting styles (Morzan using a one-handed sword-fighting style and Maul using a double-bladed lightsaber combined with martial prowess).
Both had physical appearances that revealed their cruel and haughty natures.
Both lost body parts at one point (Morzan lost the tip of one of his fingers, while Maul lost all his body below the waist).
One difference to consider between them, however, would be that Morzan was completely so, whereas Maul was not completely heartless, for Morzan showed no capabilities of even so much as caring about or even loving anyone but himself whilst Maul did have care about and/or love for at least his own biologically-related family.
In several respects he also closely aligns with the character Count Dooku, aka Darth Tyranus, of the Star Wars saga.
Both started out as members of their society's peace keeping orders of warriors. (The Dragon Riders and the Jedi.)
Both were viewed as being very talented and some of the best their orders had to offer. But eventually each became known as one of their greatest failures.
Both had received direct tutelage from renown, powerful, as well as influential masters within those orders who are often compared to each other. (Oromis and Yoda) Characters who would also notably later go on to train their respective saga's main protagonist many years later. (Eragon and Luke)
Both earlier on had a "close" relationship with an important mentor character to a leading hero who was a younger member of their order who would go on to be killed by agents of evil in service of the dark lord. (Morzan and Brom were friends in a manner of speaking in spite of the former's bullying with the latter eventually becoming Eragon's first mentor who was eventually killed by the Ra'zac in front of his pupil. Dooku was a friend and the primary mentor to the Jedi Qui-Gon Jinn who went on to be the primary Jedi mentor of Obi-Wan Kenobi who would be killed by the Sith Lord Darth Maul before him.)
Both would come under the influence of the dark lord of their society and be corrupted, going so far as to become their right-hand-men. (Galbatorix and Darth Sidious)
Both became key players in those characters' grand coups that leads to their rise to domination, including the decimation of both the order they came from and the overthrowing government in authority.
Both seemed quite loyal to their master. (Morzan is described as being the most loyal of the Forsworn, whilst Dooku is right before his death shown to be genuinely shocked/hurt when Palpatine actually turns on him. An Indicator that he did think they had a deep level of trust.)
It is at least speculated or implied that both were having tenuous feelings towards their orders even before the dark lord tries influencing them.
Both were placed in high ranking positions of leadership in a group that was key to the dark lords' plans. Both organizations notably were a group of "rebels" breaking away from some current established order. (Morzan was the head of the Forsworn up until their destruction, a group which helped Galbatorix in defeating the armies of the elves and dwarves, as well as murdering the Dragon Riders. Whilst Dooku set-up and led the Confederacy of Independent Systems before and during the Clone War in order to help create a situation where the Republic would be made desperate/scared enough to embrace Palpatine's rise to domination and his elimination of the Jedi Order.)
On a connected note when taking into account extra material each was the commander of a group of dark warriors adept in the mystic arts (The Forsworn and the Dark Acolytes) of which at least some were turncoats to the peace keeping warrior orders (Dragon Riders and Jedi) that served the villainous side. (Fighting for the Broddring Empire and the Confederacy of Independent Systems respectively)
Both characters would give a younger major character a severe wound of some kind that would act as a lasting "scar" that would go on to haunt them. Interestingly enough, they (Murtagh and Anakin Skywalker) are characters who are often compared to each other and would go on to take these men's positions as the dark lord's chief enforcer in the future after their deaths. (When he was only a child Morzan threw his sword at Murtagh in a drunken rage that left a severe scar on his back. Ending their duel during the battle of Geonosis, Count Dooku sliced off Anakin's right forearm. And as mentioned before, they would at some point in time later take the spots as Galbatorix and Palpatine's number one men.) Ironically enough both are similar wounds that would later be inflicted on the main protagonist of either saga at that future point in time by the dark lord's chief enforcer of that era. (Like Murtagh Eragon eventually received a vicious scar on his back during his battle with Durza, whilst Luke similar to Anakin had his right hand sliced off during a lightsaber duel. His being with Darth Vader in Cloud City.)
Both would ultimately be slain by a member of the order they had abandoned after a hard-fought clash of blades in an act that was in large part motivated by a desire for payback. (Brom slew both Morzan and his dragon because of his horrid betrayal of the Dragon Riders and also wanted to avenge the death of his dragon Saphira who Morzan himself had murdered. Dooku's final battle took place during the Battle of Coruscant towards the end of the Clone War where he faced off against the Jedi Knights Anakin Skywalker and Obi-Wan Kenobi. Though he managed to incapacitate the latter, the former eventually managed to best him. Though he hesitated Anakin eventually, with the help of a little bit of coaxing from Palpatine, gave in to his desire to kill Dooku for severing his arm and seemingly also because he had hurt Obi-Wan during the fighting.)
Both had extremely arrogant personalities and carry themselves with something of a regal demeanor.
Both received some hand damage in their time. (Morzan lost the tip of one of his fingers whilst during their final duel Anakin Skywalker defeated Dooku by cutting off both of his hands)
Both were immensely powerful in several fields. Both being very skilled swordsman, were adept with mental powers and a master over the mystic forces. (Magic and The Force)
As something of a "side note" so to speak, the film version of Eragon has Brom make a big deal about how he killed Morzan with his own blade. Ironically enough, in Star Wars Episode III: Revenge of the Sith Anakin used Dooku's lightsaber in tandem with his own when he decapitated him.
The Lord of the Rings
Morzan is comparable to the Witch-King of Angmar from The Lord of the Rings trilogy.
Both were once men of great importance and high standing, a dragon rider and a king.
They were both recruited by the dark lords of their worlds Galbatorix and Sauron and served as their second-in-commands.
They both had powerful winged mounts, a dragon and a Fell Beast.
Both were members and the leaders of an elite group of dark riders that were all (or nearly all) corrupted by and served their masters, the Forsworn and the Nazgul.
Both were skilled in the mystic arts.
Though he is also quite comparable to another character in The Lord of the Rings and that is the wizard Saruman.
Both were members of groups/orders devoted to protect their worlds. (The Dragon Riders and the Istari/White Council)
Both eventually became traitors however as they were corrupted and joined up with the dark lords of their worlds who serve as the main antagonists of their stories. (Galbatorix and Sauron)
Both would go so far as to become one of his chief allies, that were in high ranking places of leadership. (Though their ultimate levels of loyalty would turn out to be quite different)
Both used to be friends, at least of sorts, with a major wizardly sage character who guides their sagas' chief heroes on their journeys in the beginning. (Brom and Gandalf)
Both had a companion for a time who was a peer within his order who he treated/thought of rather diminutively. (Brom and Radagast)
Both were extremely adept in the mystic arts.
Both in terms of personality were quite arrogant and when they reached their darkest points very cruel.
Morzan can be compared to the Harry Potter character Gellert Grindewald:
Both were described as tall, handsome, and strong, yet haughty and cruel behind that facade.
Both of them had one best friend in their youth who dearly loved and worshiped them (Brom and Albus Dumbledore respectively).
Both Morzan and Gellert did not fully return their friends' affections and exploited them in subtle ways. Morzan frequently ordered Brom around, while Gellert encouraged Albus to take over the Wizarding World and subjugate Muggles.
In the end, after Morzan and Gellert murdered someone else close to their friends (Saphira I and Ariana respectively), their strong friendships with Brom and Albus would come to an abrupt end. However, while Gellert's murder of Ariana was accidental, Morzan's murder of Saphira was deliberate. It is also never proven that Gellert was the one who killed her.
As a result, both Brom and Albus would make it their goal to defeat their former best friends in an epic duel, with Morzan being killed and Gellert being imprisoned for life in Nurmengard.
In the aftermath of these duels, both Brom and Albus gained the weapon of their former friend (Zar'roc and the Elder Wand respectively). These weapons eventually came into the possession of their respective student (Eragon and Harry Potter).
The greatest difference between the two, however, is that while Gellert seemed to show signs of repentance years afterwards, Morzan did not. Also, while Albus had been in love with Gellert, Brom was in love with Morzan's wife.
Sword of Truth
Morzan, as a cruel wizard tyrant in the service of a greater dark power, is also similar to Darken Rahl of the Sword of Truth series.
Both were described as tall, handsome, and strong, yet haughty and cruel behind that facade.
Both were powerful tyrants with magic who were in the service of an even darker lord (Morzan served Galbatorix, Darken Rahl served the Keeper of the Underworld).
Both generated children who were the half-siblings of the main hero and would eventually turn against that hero (Morzan was the father of Murtagh, who had the same mother as Eragon and became his enemy, Darken Rahl was the father of Jennsen and Oba Rahl, both of whom had the same father as Richard Rahl and became his enemies).
Morzan can also be compared as Mordred, one of the Knights of the Round Table notorious for betraying his fellow brothers in arms.