Doombull

The smartest and largest Minotaurs are revered Champions of the Chaos Gods. Called Doombulls by the Beastmen, they are amongst the most feared creatures in the Old World. Doombulls are distinguished from other Minotaurs by the Mark of Chaos they wear. Only Minotaurs who are in the Chaos Champion career count as Doombulls.

These marks often affect the Minotaur’s appearance. Bloodbulls or Khornebulls have a reddish hide and skin, with heavy brass sheathing their horns. Plaguebulls, those who serve Nurgle, are bloated with distended abdomens filled with wriggling maggots and have hides covered in weeping sores and boils. Slaanbulls decorate their bodies in horrid trophies, wearing cloaks sewn from Human faces and jewellery made from Human bones. Tzaanbulls, like their strange master Tzeentch, have brightly-patterned skin, wreathes of twisting horns, and emit an aura of crackling Chaos energy.

Source

 * Warhammer Fantasy RPG 2nd ED -- Tome of Corruption (pg. 105).