Grom the Paunch
Grom, AKA Paunch of the Misty Mountain, AKA "Da Fat", was among the greatest Greenskins to have ever lived in the Warhammer Fantasy setting.
The Legend
Once upon a time, there was a group of Goblins. No more interesting than any others of their race, they found themselves without a WAAAGH to join and thus decided to have an eating contest. Deciding to up the ante, one of their number dared another, a small Goblin named Grom, to ingest troll meat. Raw troll meat, which regrows faster than almost any being can digest it. Theoretically, this should have killed him since only beings like Ogres or other trolls can accomplish such a feat and not burst. After several weeks (during which the competition went on) of excruciating pain and constant sharting, Grom's belly bloated as the meat regrew inside him. Goblins gathered around him, waiting for the inevitable explosion of gore. It never came. Grom's body adapted, and he somehow came to digest the hunk of meat at the exact rate it regrew, granting him regenerative abilities and making him larger than any Goblin, and even most Orcs which almost immediately made him the Boss of his small clan, the Broken Axe. Ten years later, he had become Warboss of almost all Greenskins in the southern Badlands which he added to his growing WAAAGH (because of course, you gotta have a WAAAGH). After claiming leadership of a large chunk of the Night Goblins by literally crushing their Warboss beneath his paunch, he lead an attack on the Dwarf lands and wiped out multiple Holds before having his minions chip away a statue of the Dwarf god Grungi into his own likeness. The Dwarfs regrouped and with reinforcements attacked WAAAGH Grom, fighting a three day battle to an ultimate stalemate. The Dwarfs sent messages to the Empire for aid, while the Goblins simply waited for more of their race (and their larger kin) to come from afar to see the spectacle of the fucking massive Goblin who's da biggest (resulting in most Night Goblins at the time joining him).
The Emperor at the time, Dieter IV, responded by immediately removing the capital of the Empire from Nuln, and moving it to the other side of the Empire to Altdorf where it remains to this day (End Times notwithstanding). The entry in the Book of Grudges as a result ALSO remains to this day. The High King of the Dwarfs responded by commanding the Dwarfs seal themselves within their Holds, and after a short time of rampaging through the Dwarf lands and unable to find anything to fight, the WAAAGH moved on.
Grom returned to the Badlands, and was joined by the more refined Greenskins who had learned the art of commerce using giant chariots the size of a small city to transport goods as well as the Goblins clever enough to tame Dire Wolves to ride. This marked the last time Grom walked like a common Snotling, and from that point forward only traveled by chariot.
By this point, WAAAGH Grom had come to resemble it's leader; large, slow, and regenerative despite any losses suffered. When Grom finally made it to Empire lands he carved a path of destruction through the countryside, obliterating any armies or communities he came across and using everything from the largest man (slaves, navigators, and rations) to the smallest stick (can never have enough dakka chariots, and chariots take a lot of wood). He mostly avoided cities until he reached his goal; old Nuln. While Dieter IV had moved his court, the former capital still shined with gilded surfaces and polished marble. WAAAGH Grom found little resistance as the populace fled before the sea of green outside the gates.
After taking the city however, Grom did the unthinkable. He stopped marching. Content to enjoy chariot races, swim in gold coins, and consume high class food from all over the worl , he began living a lifestyle that would put many Slaaneshi hedonists and Ogre Tyrants to shame.
Disgusted by his abhorrently un-Orcy behavior, his minions beginning with the Black Orcs began to desert him and attack Empire cities in small, manageable numbers. Forest Goblins, too alien and uninterested in the affairs of their kin, saw Grom's army as a distraction they could use to surge from the Great Forest and obtain food for their spider companions and masters.
The time of Greenskin prosperity came to an end when Prince Wilhelm, cousin to the Emperor, raised a militia army and purged Greenskins from Reikland. Only the crops grown that year in the reclaimed fields saved the Empire from complete collapse. Grom, content to be the only Greenskin to have held court within an Empire city, was finally roused to battle when the voice of Gork himself (or possibly Mork) spoke to him through his Shaman Ol'Blacktoof, telling him "GO WEST YOUNG GIT!" Grom immediately commanded all Greenskins within shouting distance to mount their chariots and ride to the coast. His army completely stampeded the army of Middenland, although after Grom's chariot was destroyed by a cannonball he ordered his forces into the city of Middenheim. The populace was left completely unharmed, as the only thing the Greenskins sought was the finest wood available. The temple of Ulric lost it's roof, and the city retained everything else as Grom's only desire was a replacement chariot.
After reaching the coast of Nordland, Grom demanded his boyz build ships. More ships than had ever been built by green hands were constructed, entire forests vanished almost overnight while Orcs looted entire villages, buildings and all, and were rebuilt as they had been before on the decks of the sea hulks. Many of the remaining Black Orcs, uninterested in Grom's plans, found themselves as slaves and meals to their frenzied smaller cousins.
After several months the massive fleet disembarked, and traveled south towards Marienburg. The Imperial fleet engaged them there, and after losing half their forces a freak storm kicked up which blew both fleets away from the city. The bulk of the Greenskin ships sunk immediately, having been made of da best (green) wood. For forty nights, Grom's own ship was tossed about on the ocean waves until it finally broke apart on a shore covered in mist. The survivors discovered they were in Yvresse, on Ulthuan. A land completely shrouded in magic that islands came to life and attempted to sink ships, in a region where that same magic manifested Daemons into existence when the (non-magic) wind blew. Grom was the first, and last, WAAAGH to reach the birthplace of the Elvish race.
Very few of Grom's animals had survived the cruise; a handful of the most feral Wolf alphas who had consumed their packs to survive and one Wyvern, which would only obey Ol'Blacktoof. Although the Greenskin numbers were low, Yvresse was the least populated High Elf kingdom and thus even the warband of the Goblins and few Orcs remaining outnumbered the army of the city of Tor Yvresse, the only major settlement. Ol'Blacktoof, who had become a very powerful wizard by this point, sensed the Waystones of the land drained magic from the world and informed Grom they should be destroyed. Each one that fell destabilized the magic of the world more, warping reality and causing an aurora borealis effect of deadly beams in eight colors at all times. Drawing the energy into himself, Blacktoof lost himself more and more as the voices of Gork and Mork (or Mork and Gork) grew more and more distant and other voices grew louder.
Grom had an archenemy in the form of Git Guzzler in earlier editions, although it was unclear if Grom ever actually knew Git existed or what happened to Git after Grom died.