Bullgor can refer to one of two things in the greater Warhammer multiverse.
In the original Warhammer Fantasy, "bullgor" was a fan given nickname to gors who have distinctly bovine features without being slaangors or actual minotaurs - in-universe, these were known as bovigors; stated to be rarer than "caprigors", the goat-featured "common" beastmen", they often got on exceptionally well with minotaurs, but mechanically they were no different to standard gors.
Warhammer Fantasy (Minotaurs)
The Minotaurs of Warhammer Fantasy were a bovine form of beastman, not to be confused with older lore stating that Slaangors often mutated to look more bovine. Mindless, bloodthirsty carnivors, a minotaur on the tabletop was a fucking rape train, half-bull half-man killing machine employed by the chaos furries. Their generic characters the Doombull and Gorebull are Minotaur characters able to be even more fucking rapetastic shit because they're the strongest and smartest of their kind.
Taurox was a named Minotaur character who was favored by Khorne, despite being a beastman, aka the unwanted bastard children of the dark gods, meaning he was epic as shit to be noticed by the higher up. Sadly, he got shot down by Markus Wulfhart.
The most in-depth and interesting lore about minotaurs is found in the original Realms of Chaos books - specifically, The Lost and the Damned, where all the beastmen were introduced. This even gave you rules to play as Minotaur Chaos Champions on the Path to Glory, and in this Minotaurs were luckier than their Centaur and Dragon Ogre counterparts, as they maintained the ability to be army leaders in future editions of Warhammer. Ironically, they also gained the ability to become spellcasters by devoting themselves to Tzeentch in later editions, when originally they (and Dragon Ogres) couldn't become wizards.
Ironically, minotaur champions are the least mutation-prone of any Chaos Champion in this edition; when generating them, the basic minotaur starts with only a 10% chance of having 1 Chaos Attribute, and this chance increases by 5% per 5 levels. Only minotaur champions generated at levels 15 (D3), 20 (D4) and 25 (D3+1) start with potentially more than 1 Chaos Attribute.
Like Beastmen Champions, Minotaur Champions have their own unique retinue generation table, representing their unique position in the forces of Chaos, their inherent power, and their domiciles:
- 01-01: D6 Beastmen (if the Champion has a Mark of Chaos, they share his Mark, otherwise they're generic Beastmen)
- 11-20: D6 Beastmen
- 21-25: Beastman Hero, potentially Chaos-marked (if the Champion has a Mark) and/or with beastmen followers.
- 26-30: Beastman Shaman
- 31-25: D4 Centaurs
- 36-40: D3 Dragon Ogres
- 41-80: D6 Minotaurs
- 81-90: Other Followers (Roll on the Human Champion Retinue Table)
- 91-00: Monsters - Roll another D100 and compare to the results below.
- 01-04: Chimera
- 05-08: Cockatrice
- 09-11: Dragon
- 12-15: Giant Eagle
- 16-20: Giant
- 21-23: Gorgon
- 24-27: Griffin
- 28-31: Hippogriff
- 32-35: Hydra
- 36-39: Jabberwock
- 40-43: Manticore
- 44-48: Giant Spider
- 49-52: Giant Scorpion
- 53-55: Treeman
- 56-59: Wyvern
- 60-63: Chaos Hounds
- 64-68: D6 Giant Rats
- 69-73: D6 Skeletons plus an Undead Chaos Champion
- 74-78: Snotling Swarm (D4 Bases)
- 79-83: Warhounds
- 84-88: D4 Ogres
- 89-92: D6 Fimir
- 93-97: D4 Zombies plus an Undead Chaos Champion
- 09-00: Roll twice on this chart.
Age of Sigmar
In AoS, they're back under the more copyrightable name "Bullgors". Not much has changed, only instead of them pissing and shitting everywhere in forests in the Old World, it's across all the mortal realms.
A Doombull is a Minotaur Lord-tier character in Warhammer Fantasy, which was introduced in the original Beasts of Chaos splatbook for 6th edition. When Beasts of Chaos was supplanted by Beastmen, the Doombull gained a Hero-tier counterpart in the Gorebull.
The name is actually taken from the original Realms of Chaos duology, where a Minotaur Hero went through the titles of "Bloodkine", "GoremasteR", "Deathsteer", "Doombull" and finally "Minotaur Lord" as it gained levels, starting as a lowly Minotaur and gaining a new title at every 5th level.