Gorthor
"Horn and hoof, power is there. Not feeble smoothskin, clumsy Greenskin, wicked elf-swine. Gor is strong. Gor is true. Gor shall kill all, slay all for the gods!"
- – The (Beast)man himself
"I fear no man, but that thing... it scares me."
- – The Heavy, Team Fortress 2: "Meet the Pyro"
Gorthor the Beastlord (aka Gorthor the Cruel, which was also his name in the Dark Tongue) was a Beastlord from amongst the Beastmen and effectively fills the role of Gorbad Ironclaw or Grom the Paunch for his race, i.e. the ancient paragon of destruction that everyone's trying to copy. Combining the body of a hulking bruiser with the mind of a cunning genius, Gorthor was responsible for leading a massive rampage across The Empire before his death during the Siege of Hergig in a mutual kill duel against Mikael Ludendorf, the then-Elector Count of Hochland. By then the damage had been done, however, as Gorthor's massive war effort almost completely depopulated the Imperial provinces of Ostland and Hochland before he was finally stopped, and some parts of them remain unsalvaged because no-one has the stomach to go and reclaim them.
There were two things that made Gorthor distinct from other Beastlords: one, he was favoured by the Chaos Gods themselves and often received apocalyptic visions of Beastmen trampling the world of man completely into the dust from them; and two, he freely violated the few rules Beastmen have (like don't put your hands on a Bray-Shaman, ever, which he did repeatedly to those who spoke against him and had their skins woven into a hypnotic cloak because he was convinced he had the clout with the Gods to pull that shit off) and convinced everyone to go along with it. It can't be emphasized enough that he was a figurative and literal monster even among the race that only exists to be both. Very few Beastlords in subsequent decades have come close to either his murderous prowess, his sheer size or the bodycount left in his wake.
Gorthor can, in many ways, be considered the Beastmen equivalent of Azhag the Slaughterer; an incredibly powerful warrior-mage whose role in the narrative is as the absolutely terrifying historical leader of his villainous faction, but who was canonically killed off long ago and whose mantle may now be passing on to a new figure - Khazrak for Gorthor, Grimgor Ironhide for Azhag.
Alongside Khazrak, Gorthor is one of the two oldest Beastmen special characters, having debuted in 5th edition's Champions of Chaos.
The (Beast)Man, the Legend
In 5e, Gorthor's lore was very minimalistic - a mere four paragraphs. They've fleshed it out a fair bit since then.
No-one really knows where he came from - not that you'd need to, as if you know anything about where baby Beastmen come from, you can make a pretty good guess. Plus there's no evidence he was actually affected by it. He was probably just born with the attention of the Dark Gods and that's as good an explanation as any.
Gorthor rose to power the Beastman way, by challenging every warrior higher ranked than him until he led his own Bray-Herd. Then he set about building up his Herd's strength by assimilating other Herds, even fighting and killing Bray-Shamans who spoke against him, which was and still is unthinkable for most Beastmen. Despite this, he kept the favour of the Gods, and the Beastmen continued to follow him, until eventually he raised all the Beastmen between the River Lynsk and the Middle Mountains and suddenly attacked the Empire's northern provinces. He burned a tail of destruction through Ostland and Hochland.
At one time, his Bray-Herd ran into an Orc WAAAGH! including a massive number of Black Orcs. They naturally took great offense to each other's existence, and two tides of fury and muscle crashed into each other in a flurry of CQC and loud shouting. Gorthor treated his fight with the Black Orc Warboss leading the other army as no big deal until the Dark Gods warned him that this particular green lunatic was a rival for his role as world-ender and he needed to step up his game. So he did, with the Warboss becoming a trophy for Gorthor's chariot and armour.
Gorthor nearly completely obliterated Hochland's capital city of Hergig, before being destroyed when crusading knights arrived to assist the defenders.
On the Tabletop
Gorthor has appeared in three editions - 5th, 6th and 7th - and in all his depictions he is a Mounted Lord who always appears on beastman chariot pulled by tuskgors, wielding his three iconic magical items; the Impaler, the Skull of Mugrar, and the Cloak of the Beastlord.
5e
Gorthor costs a whopping 620 points to field - 510 for Gorthor himself, 110 points for his chariot. His chariot is equipped with scythed wheels, is pulled by two tuskgors, and is driven by the charioteer Bagrar the Tamer, who adds +d6" to the chariot's Pursuit move so long as he remains alive.
Gorthor himself has M 4, WS 6, BS 4, S 4, T 5, W 4, I 5, A 4 and LD 10. He is a Master Shaman, equipped with 3 spells taken from the Chaos or Dark Magic decks, and has the unique special rule Beastlord, which makes all beastmen regiments within 12" immune to the effects of Infighting.
The Impaler is a magic spear that grants Gorthor +2 Strength on the charge. Additionally, in any round in which Gorthor a) lands all 4 attacks against the same model, and b) all of his attack rolls are a 4+, the model he is targeting is killed outright with no saves of any kind allowed.
The Skull of Mugrar is a minotaur's skull that inflicts a baleful curse on Gorthor's enemies; all enemy models in base contact suffer a -1 penalty on to hit rolls and to wound rolls for attacks made against Gorthor.
The Cloak of the Beastlord is made from the skins of bray-shamans that Gorthor defeated in sorcerous duels. Roll a d6 at the start of the battle; the Cloak will negate that many wounds inflicted against Gorthor, his chariot, Bagrar or the tuskgors pulling it.
6e
In this edition, Gorthor lost his direct shamanic powers, but became more or less the Beastmen Archaon. He sports a statblock of M 5, WS 7, BS 3, S 5, T 4, W 3, I 6, A 4 and LD 9. He rides a custom chariot, which thusly has S 5, T 5, W 4 and a 4+ armor save. He costs 463 points and has the following special rules and equipment.
Ambush & Raiders: These two special rules are the standard rules for 6e Beastmen, although Raiders only applies if Gorthor is on foot.
Mark of the Gods: Gorthor can re-roll failed Break and Psychology tests, and if on foot, any unit he joins has this ability too. Marked and Daemonic units of any Chaos God may freely join an army led by Gorthor.
Bagrar the Tamer: Gorthor's highly skilled charioteer allows Gorthor's chariot to reroll all Fleeing and Pursuit distance rolls.
Beloved of the Gods: Gorthor adds +1 Dispel dice to the Dispel pool. Additionally, at the start of each Magic phase, roll a D6 and compare the result to the Lore of Death magic table; Gorthor can cast the resultant spell as a Bound Spell with a Power Level equal to its casting value. He cannot exchange these results.
The Favored of Chaos: Gorthor's army has +1 Rare unit slot for its size.
The Impaler: Magic Weapon and Spear. Additionally, any attack rolls that are doubles, triples or quadruples wound automatically, even if the roll would normally be a miss.
Skull of Mugrar: So long as Gorthor is mounted on his Chariot, Hits against him have their Strenth capped at 5 (ie, any Hit with a Strength of 6 or higher is just treated as a S5 hit) and ignore the multiple wounds trait if they would normally benefit from it.
Cloak of the Beastlord: Against attacks directed specifically against Gorthor, not his chariot, Gorthor always has a Ward Save equal to the Strength value of the attack against him, to a maximum value of Ward Save 6+ against S6 or higher attacks.
7e
Technically building on from his 6e depiction, the 7e version of Gorthor is probably the simplest he's ever been depicted.
In 7e, Gorthor's stat block is M 5, WS 7, BS 3, S 5, T 5, W 3, I 5, A 5 and LD 9. He has the special rules Primal Fury, Man-bane, Chariot and Scion of the Dark Gods (Gorthor randomly generates a Lore of Death spell as a Bound Spell, power level = 1/2 casting value, at the start of each friendly Magic phase). His magic items are The Impaler (Magic Spear, grants Killing Blow), Skull of Mugrar (Gorthor's chariot does +1 Impact Hit dice and chooses the highest result), and Cloak of the Beastlord (if Gorthor is general, friendly units can use his Leadership from 18" rather than 12").