King Whomp

King Whomp is the boss of Whomp's Fortress, and is a larger boss variant of the Whomp enemy. He is found on top of Whomp's Fortress in the Chip Off Whomp's Block mission. They must be defeated by ground pounding their back 3 times, which will reward you with a star. He attacks the same way as regular Whomps.

King Whomp Rematch
There is supposedly a second fight with King Whomp in Tick-Tock Clock, found in an out-of-bounds room only accessible by clipping. Upon beating King Whomp, they would drop a star. Notably, in The Starry-Night Skies, King Whomp can appear there as a mini-boss as well. Upon defeating them, they commonly drop a singular red coin, though it has been documented that they drop a regular star as well. They can also appear in Flying Fortress with unique dialogue.

Whimps
In Super Mario Galaxy 2's fight against King Whomp, he spawns miniature Whomps named Whimps, officially known as Pattan. They rush at the player, attempting to crush them, like any other Whomp. In some personalized copies of Super Mario 64, Whimps can appear and act identically to their appearance in Super Mario Galaxy 2, potentially explaining their appearance in said game as being a recreation of an unused asset.

King Whomp Rematch (DS)
In some personalized copies of Super Mario 64 DS, if Waluigi is unlocked, he cannot be ground pound, requiring a unique fight against King Whomp for Waluigi. Like in the original Super Mario 64, this can reportedly occur in Tick Tock Clock, but why is unknown. This rematch usually requires Waluigi to kick King Whomp to knock him down, dealing damage as if they were ground pounded due to them slamming on the ground and getting cracked. Alternatively, they could use other reported abilities, such as throwing Bob-ombs to damage King Whomp or punching them with the Magic Gloves. Why King Whomp would have a unique rematch for Waluigi even though Waluigi is consistently unlocked way after the boss' relevancy is not entirely understood, unlike Big Bob-omb's rematch as Mario can pick up Big Bob-omb but Yoshi cannot, as Mario is unlocked shortly after Bob-omb Battlefield.