The Tyrant is the one responsible for making all the important decisions within his tribe (usually under the advice of a Butcher), such as who they are going to fight against/for, if they are going to declare war on another tribe and so forth.
Notorious Ogre Tyrants
Below follows a list of some of the most famous Tyrants to have existed.
The most powerful tyrant at the moment is Greasus Goldtooth, the Overtyrant of the Ogre Kingdoms. Having subjugated all the tribes living in the mountains surrounding his own kingdom, Greasus has imposed multiple laws upon his kingdom; for example, it is now prohibited to assault any trade caravans passing through the Overtyrant's kingdom.
Blaut Feastmaster, the heavily-jowled the Tyrant of the Feastmaster tribe, became famous after he, having traveled into the Empire, brought back an entire string of enslaved Halflings to his tribe (instead of eating them when he caught them). These Halflings now perform the same duties as the Gnoblars of other tribes.
Shrewd Fulg is the leader of the aptly named Tribe of Shrewd Fulg. Although far from the most powerful Ogre physically, Shrewd is as cunning and evil as a an Ogre can be expected to be, and rules the north-western parts of the Ogre Kingdoms with an iron fist. Anyone who opposes him inevitably wind up dead from food poisoning or get "accidentally" eaten by one of his many pet monsters. Shrewd also has close connections with the Skaven Clan Moulder, and his servants live in perpetual fear of waking up to find themselves transformed into Rat Ogres, or something worse.
The Mountaineater Tribe is ruled over by Bauldig Mountaineater. During an attempt to scale Mount Thug, Bauldig came across an opening in the mountain. Although none knows for sure, Bauldig claims that inside the crevice he came across the heart of the mountain; a giant warrior of stone whom the Mountaineater claims he slew and ate. As proof of this, Bauldigs skin has taken on the color and consistency of rock. As a result, his servants regularly eat rock with any food they ingest, in the hope that they will become as Bauldig himself one day.
The Great Tribe of Ghuth Spawnchomper, ruled by the same, live in the northern wastes of the world, where they attack, kill and eat anyone they come across. Ghuth himself, in particular, has become heavily affected by Chaos; not only has he grown a crown of gesticulating fingers across his brow, but he has also begun to recruit Dragon Ogres into his tribe, despite the loathing Ogrekind in general has for the creatures.
The waypost of the the Sentinels are the last stop for any caravan hoping to cross the Mountains of Mourn. The waypost is ruled over by the Eyebiter Tribe, which in turn is ruled over by Grandfather Malron Eyebiter, an Ogre who, supposedly, has sired more children than any other Ogre in history.
The Ironskin Tribe live in the north of the Mountains of Mourn, and have a strange fascination with metal, valuing the metal more than they do gold. The tribe, under the leadership of Ghark Ironskin, have set up expansive trade agreements with the Chaos Dwarfs of Zharr Naggrund, and thus have access to more Leadbelchers than any other tribe, and Ghark himself ride into battle on top of a huge mechanical rhinox, whom some claim has been possessed by a daemon.