The Prisoner (aka The Hero of Kvatch, and later Champion of Cyrodiil; ultimately Sheogorath)
A prisoner in the Imperial Prison that was lucky enough to cross paths with Emperor Uriel Septim and the Blades. After escaping and witnessing the Emperor's assassination, they are tasked with delivering the Amulet of Kings to Jauffre.
Skyrim further implies that the player character canonically ultimately became Sheogorath, dropping small hints that he may have been involved with the Dark Brotherhood questline (he mentions a severed head) and Thieves Guild (he mentions a fox).
Karma Houdini/Villain with Good Publicity: Perhaps. References in Skyrim suggest the Champion may have joined both the Dark Brotherhood and Thieves Guild; despite that, they still get hailed as a hero and rewarded with near god-like power. As always, however, the truth is left ambiguous.
The Call Knows Where You Live: It's implied that no-one, not even the Champion, seems to know exactly why they were in that prison cell at the beginning of the game. Martin Septim believes that this was no mere coincidence.
Charles Atlas Superpower: Simply using a spell/skill a lot can make the player have incredible strength, the ability to jump impossible heights, run faster than a charging bear, among many other traits.
Deity of Human Origin: Apparently the first mortal to become a Daedric Prince. note Trinimac the Aedra, who became the Daedric Prince of the Scorned, Malacath, was technically mortal but still more than just an elf, more of a demigod.
The Dreaded: The Champion can become this to their enemies.
Impoverished Patrician: In the Fighter's StrongholdDLC, Castle Battlehorn is bequeathed to the Champion after defeating it's would-be invaders. Lord Kelvyn, the previous owner, had sold most of the Castle's wealth to pay for it's upkeep, with his will explicitly stating that he hoped that the Champion would refurbish the Castle back to it's former glory.
Similarly, the Wizard's Tower DLC has Frostcrag Spire being bequeathed to the Champion by a distant relative. Since it's mostly unfurnished, they're required to bring the tower back up to snuff.
The Lancer: Uniquely enough for an Elder Scrolls Protagonist. He plays this role to Martin.
Silent Protagonist: Pretty much. Despite having the occasional line of text, your character isn't voiced aside from grunts and yells in battle.
Villain Protagonist: Depending on how you play. There's no reason why you can't go around punching everyone you see, and still save the world. And the Dark Brotherhood quest line is very much intended to let the player be a villain.
The Emperor of Tamriel. The player meets him at the beginning of the game, as he is escaping from a group of assassins through a secret passage in the Imperial Dungeons. His attempts to flee are futile, and he is eventually killed, but not before handing the player the Amulet of Kings, which starts the main storyline of the game.
Nice Guy / Nice to the Waiter: He's unfailing polite to the player at all times, even rebuking his bodyguards after they insult you and suspect you of being an assassin sent to kill the Emperor. Somewhat justified however, since he's long since dreamt of your meeting, hence his inexplicable faith and trust in you, a lowly prisoner at the time.
The last surviving son of Emperor Uriel Septim, Martin was raised as a priest in the city of Kvatch. After the Emperor's death, daedra invade Kvatch in order to hunt Martin down, but he is rescued by the player. Despite being reluctant at first, he grows to suit the role of Emperor.
The Atoner: He used to be a Daedra worshipper - even a previous owner of one of their legendary artifacts - but when you meet him, he's a quiet and humble priest.
Badass Bookworm: He spends most of the game at Cloud Ruler temple, poring over old tomes to help the player retrieve the Amulet of Kings, but proves himself quite a capable combatant in the Battle of Bruma.
Big Good: Being the only one who can seal the gates of Oblivion and Emperor of Tamriel.
Bling of War: His Dragon Armor, which is essentially a set of Imperial Legion plate reworked in solid gold.
The Chosen One: The only person who can save the Empire by lighting the dragonfires and closing the gates of Oblivion.
Doomed Hometown: He was raised in Kvatch, which is on fire and full of daedra by the time the player reaches it.
The Hero: Of the story. The Hero of Kvatch is actually his Lancer.
Heroic Sacrifice: Martin gives up his soul to become an avatar of Akatosh to defeat Mehrunes Dagon at the end of the main quest.
Fire-Forged Friends: at the start of the game, he is rude and distrustful of you(justified, since you were a prisoner at the time), but by the time he helps you getting a clue to find the Mythic dawn's location, he starts to act more friendly with you. And if he survives the meeting, he even calls you friend.
An Altmer mage, leader of the Mythic Dawn cult, and bent on summoning Mehrunes Dagon to Tamriel. Writer of the "Commentaries on the Mysterium Xarxes".
Consummate Liar: He's obviously not telling the whole truth. The real son of the Camoran Usurper was a Bosmer, and his list of Daedric realms and their rulers contradicts several other sources. His speech to the Mythic Dawn about Paradise is also more than a tad misleading. He's damned good at sounding believable, though.
Don't forget his speech if you walk into Paradise after completing the Shivering Isles. He'll have no idea you're now Sheogorath!
The Dragon: To Mehrunes Dagon. Camoran's children, Raven and Ruma, are his Dragons.
The Heavy: He's the most active villain in the game, until the end when Mehrunes Dagon is summoned.
Hannibal Lecture: As you travel through his paradise near the end of the main quest, you hear his voice in your head remarking on the futility of your actions and the true nature of the Daedra Lords and the Nine Divines. Apparently, Tamriel is just another plane of Oblivion, and the Nine are traitors to the Daedra Lords, the true gods of the universe.
Though considering the amount of mistakes in the speech and holes in his backstory, he might just be a liar or badly informed.
Manipulative Bastard: Oh, boy. He told his followers the Mythic Dawn that they'd go to paradise. Turns out, this paradise is only for him, while his followers are tortured there and unable to die.
Cruelty Is the Only Option: His "favor" involves freeing an Ax-Crazy Xivilai named Anaxes, who had been imprisoned by a group of Ascended Immortals, and allowing him to continue killing his captors.
Deadpan Snarker: If the Player chooses to fight him for the Bands instead of doing his favor, Kathutet responds with this:
Kathutet:"Your mind follows the simple path ... the choice of an animal. You see an enemy and you attack it, unthinking. But you have courage, at least. To slay a bold animal like you is not without glory."
Jerkass: Being a Daedra, it's only s natural for him to despise mortals.
Punch Clock Villain: One of the reasons he agrees to help you on your quest is because he despises Mankar Camoran as much as you do, and couldn't care less if Camoran's plans succeeded or not.
Worthy Opponent: He sees the player as this, for defeating his fellow Dremora in the siege of Kvatch, and destroying their tower. This is also the other reason he agrees to help you in your quest.
Kathutet: You destroyed the Sigil Tower at Ganonah. My kin say you fought well.
Player: Ganonah? I've never heard of it.
Kathutet: Our clan sacked your city of Kvatch... a trifling task fit for scamps. Your swift retribution earned you much respect among my people. We had not expected that a mortal would act with such resolution and honor. It is no dishonor for us to speak.
Daedric Prince of Destruction and the leader of the Daedric forces invading Tamriel. Worshipped by the Mythic Dawn as a god. Appears in the flesh at the end of the Main Quest in a last ditch attempt to stop the lighting of the dragonfires, forcing Martin to perform a Heroic Sacrifice to defeat him.
The Voiceless: Despite being the main antagonist (and being the only Daedric Prince (bar Sheogorath) that we see in the flesh), he never speaks a word in the game. Strangely, all his other appearances (Battlespire, Morrowind, Skyrim) have him speak.
A Daedric race of humanoid warriors that are native to the Deadlands. They serve as the enforcers of Mehrunes Dagon during the Oblivion Crisis.
Black Knights: Their warriors tend to wear full body armor, complete with face-concealing helmets.
Blood Knight: They love to fight, and are extremely aggressive towards non-Daedra.
The Smurfette Principle: This trope hit the Dremora race very hard. Female Dremora are extremely rare, since the few females in the entire game are:
1.) Archers, which are only found inside certain Oblivion Gates. This means they can only be encountered before the "Light the Dragonfires" quest is finished.
2.) Members of the Markyn, which is the second-highest rank in Dremora society. Thus, they will only be encountered by a high-level player.
3.) There is a chance that a Kynmarcher, Valkynaz, or even a male Markynaz archer might appear in their place instead.
4.) Due to a minor oversight in the game's production, they are all completely silent, and don't even have dialogue or even audio files assigned to them; Any attempt to converse with a female Dremora will yield the infamous "I HAVE NO GREETING" message, and will make no sounds during combat.
Game-Breaking Bug: Oh dear... sometimes, the game doesn't remove him from the Fighters Guild properly when he joins the Blackwood Company. When you kill him at the end of the quest, you will be expelled from the guild for killing a fellow guild member, despite the fact he went hostile towards you. There are very few ways around this- either go outside and let a city guard kill him, or use the console to reset your guild murder status to avoid expulsion. It's not known what causes this... certain game mods may interfere with scripts, but it's also known to happen in an unmodded game for some players.
Informed Ability: Said to be nearly invincible, but is only slightly more powerful than the average necromancer.
The Worf Effect: When the player finally faces him, he appears to be a typical Altmer mage in some regular necromancer robes. Compare this to his appearance in Daggerfall, where he was a menacing hooded figure with Glowing Eyes of Doom.
Just Like Robin Hood: The beggars of the Imperial City are all under his protection. In return, they serve as his spies.
Ret Gone: The cursed cowl he's forced to wear makes all traces of his existence vanish, even if he goes right up and reveals his identity to someone (which he apparently did to both his wife and you, but the curse pretty much erased that from history). He's always and simply "a stranger".
Shrouded in Myth: Mostly due to him supposedly living for over 300 years (because the cowl's curse makes it seem as if the same person has always been The Gray Fox, no matter how different each Fox is from the last).
Equal-Opportunity Evil: The lineup consists of a vampire, two Argonians, a Khajiit, an Orc, a Wood Elf (the last two of which are sleeping together) and a Breton, diversity that would make any other guild hang its head in shame.
And that's all in one Sanctuary, too! Outside of there, you can find two Imperials, a High Elf, a Nord, another Khajiit, an Argonian, two Dark Elves, another Breton, and another Wood Elf, who's the leader of the whole Brotherhood.
Highly-Visible Ninja: Gogron's too big and clumsy for sneaking, and too unsubtle to care. He just kills anything between him and his target, even forgoing the Brotherhood's trademark Shrouded Armour to help him do so.
Woobie, Destroyer of Worlds: Antoinetta Marie had a miserable life until she was welcomed into the Brotherhood, but now she's terrifyingly chirpy about killing large numbers of people.
Voiced by: Ralph Cosham
Ax-Crazy: He kills his lover after she learned at least part of the truth of his insanity, his work with the Dark Brotherhood, and his attachment to his dead mother's head. In his own words, there wasn't enough left of her for any one to find. He then proceeds to kill most of the Brotherhood and has an unhealthy obsession with the color red...
Big Bad: Ungolim, the Listener. Also, the Night Mother.
The Dragon: Arquen, a Speaker who leads the other Speakers toward the end of the quest line. Also, every member of the Black Hand has their own personal Silencer. Shaleez and Havilstein Hoar-Blood are two of them, as are two of the three Speakers at the end.
The Starscream: Mathieu Bellamont, Speaker at endgame, and Silencer before that.
Suicide by Cop: If you do the sidequest where he learns of his heritage, he won't even flinch when you fight him for the title, though he does defend himself eventually if the fight drags on too long, saying "I don't care about my heritage! I won't die like a beast!"
The Adoring Fan
Voiced by: Craig Sechler
A small wood elf fan the player gains after becoming the Grand Champion of the Arena, who can follow you around and worship you.
Anime Hair: His bright yellow "Hershey Kiss" shaped hair (as the Strategy Guide describes it) is his most noticeable physical trait.
Joke Character: Though he'll follow you anywhere (even into Oblivion), he'll run away when you get into a fight.
Mythology Gag: Seems to have become one for Bethesda Softworks, with an identically-voiced expy named Sticky, appearing in Fallout 3. In Skyrim, a passing reference is made to a past Arena Champion who was murdered by a supposed 'Adoring Fan', in reality a member of the Dark Brotherhood. By Azura!
Not Completely Useless: As annoying as he can be, he does take out a torch whenever it gets dark, freeing up a hand for the player. Of course, there's still the issue of him running away, which can be remedied with a Rally spell.
Sour Supporter: He can be. If you lower the Adoring Fan's disposition enough — training up your pickpocketing skill on him will do the trick — he'll constantly sneer at you.
Proper Lady: Supposed to be one. The in-game loading screens describe her as "lovely and cultivated" and she's known to pay visits to her mother and the chapel regularly. Sanguine describes her castle as a "dull, dreary place".
Countess Millona Umbranox
The Countess of Anvil, whose husband, Corvus, vanished mysteriously ten years ago, leaving her in control of his lands.
The Count of Cheydinhal and the only non-Imperial among them. His son is something of a Miles Gloriosus who tries to close an Oblivion Gate and goes missing. He's also rumored to have had his wife killed twenty years ago.
Nepotism: Accused by Countess Caro of having gotten his appointment due to his connections to King Helseth and Queen Mother Barenziah of Morrowind. Not exactly a reliable source, though, considering her racism.
Screw the Rules, I Have Money!: Played with. The loading screens indicate that he's taking bribes from the Dark Brotherhood to keep quiet about their presence in his town, but knowing them they didn't give him much choice in the matter.
Nice to the Waiter: Played with. Sheogorath happily encourages the player character to do things like repeatedly and unnecessarily summon his eternally put upon Chamberlain, insisting that Haskill "loves it" and doesn't feel appreciated otherwise. On the other hand, he also regularly praises Haskill's intelligence, loyalty and fashion sense, referring to him as dear and a friend. Sheogorath is also surprisingly slow to punish another character who openly promises to betray him, and genuinely fond of his Realm and its inhabitants. Not that any of this in any way negates him also being ultimately inhuman and unspeakably dangerous.
OOC Is Serious Business: Sheogorath stops all joking, overreacting and non-sequiturs just before his transformation into Jyggalag. He's not Jyggalag yet, though, meaning that his despair over the fate of the Isles and his apparent failure to save them is genuine.
Silver Fox: There are several characters of both sexes scattered around Cyrodiil and the Isles (but mostly the Isles) that get a little fluttery over the Madgod.
What Beautiful Eyes / Hellish Pupils: By all appearances a normal-seeming and handsome older gentleman with odd fashion sense...except for his eyes, which are black with yellow irises.
He shares an eye model with the Mania-side soldiers known as the Golden Saints, which may be confirmed in the game's Construction Set. Assorted hints such as the existence of dual torches for the Flame of Agnon, a loading screen referring to Mania and Dementia as factions with one or the other "currently" in favor at any given time, and Sheogorath's palace being located significantly to the Mania side of the Isles' dividing line (visible from a high enough vantage point outside the city) appear to imply that he favors his Mania side during the events of the DLC. Hence the eye color favoritism.
Voiced By: Jeff Baker
Berserk Button: Mehrunes Dagon specifically and mortals oversimplifying the politics of Oblivion in general. During the interview mentioned in the elderly immortal entry below, a question that touches both of these drives Haskill into a rant he describes as "excessive".
Blue and Orange Morality: Casually refers to decency and morality as "provincial notions." It's a daedric realm, after all.
Brown Eyes: Trustworthy, stable and down-to-earth? Check, check and check.
Elderly Immortal: Bethesda's Interview With Two Denizens of the Shivering Isles reveals that he has been serving his master since "the beginning." Despite this he appears in the form of an aging Breton.
Interspecies Friendship: His attitude towards the player character improves greatly over the course of the game. Although at the end of the storyline the "interspecies" part becomes questionable and rather complicated.
Stiff Upper Lip: Although he can be snappy or a bit gloomy about it, and immediately after Sheogorath "dies" to become Jyggalag his script notes in the game engine state that he "Regains composure and ressumes his character." So it's not quite 100%.
Blood Knight: The Golden Saints are considerably more aggressive than the Dark Seducers, especially in combat against the latter.
Can't Argue with Elves: The Golden Saints treat all mortals that inhabit the Shivering Isles, and even their own male counterparts as completely inferior beings, and make no attempt to hide this in their interactions.
Dark Is Not Evil: The Dark Seducers, which are actually more polite towards mortals than the Golden Saints. Then again, considering that they serve the side of the Isles that favors secrets, cruelty and treachery, it may not be in one's best interests to take them at face value.
Light Is Not Good: Despite their name, Golden Saints are anything but saintly. More broadly, canon states that no daedric entity can truly be classed as good or evil.
Tiny Guy, Huge Girl: The males of both races are roughly the same height as Imperials, while the females are equivalent in height to the Altmer and Dremora, which are consistently the tallest races (playable or otherwise) in the game.
Knights of the Nine characters
Voice By: Wes Johnson
A hero from the early First Era who helped the Nedes rebel against Ayleid tyranny.
His behavior is pretty odd too. He often enters ruins and caves to search for calipers for 5 hours (which has likely startled some players), enters Valenwood along his route between Anvil and Leywiin, and has been known to occasionally chase deer.
Take That: Just about every speech he makes is a reaction the makers have about an aspect of the game fans aren't pleased about. An example is the fact throwing weapons are removed. M'aiq responds to this by saying that if people hold their weapon, they only need one.