Wiggler often appears as an underling of Bowser in the Mario games and media. It is a caterpillar with spherical segments.
Super Mario 64
Wiggler was a minor boss in the level TinyHuge Island. To access Wiggler's chamber, Mario had to grow large, then ground-pound the top of the island, smashing open a small hole, draining a torrent of water into the chamber. Then Mario would have to shrink in size to enter the chamber. When he does, he finds Wiggler, who is angry at Mario for flooding his home, and claims that everything went wrong since Bowser gave him a Power Star, and that the star makes him feel strange. Mario had to defeat Wiggler by stomping on him three times. After that, Wiggler would admit defeat, give Mario the star, and claim that he felt better.
Super Mario Sunshine
Wiggler appeared as a boss in the third level of Gelato Beach. Enraged at being knocked of the Sandbird's tower, it goes beserk and charges around randomly.
In this game, Wiggler was incredibly heavy and could send Mario flying by building up momentum, and then, ramming into him. It could only be defeated when Mario watered the dune bud sand castles to make them grow, and having Wiggler trip over them, sending him flying onto his back. Mario could then ground-pound a section of his stomach.
Mario and Luigi: Superstar Saga
Once again, Wiggler appears as a boss, this time in the Chucklehuck Woods. Mario and Luigi are forced to stomp on Wiggler to get around him. Wiggler gets angry, and blocks the bros. path, and has to be defeated.
Mario and Luigi: Partners in Time
Wiggler made an appearance as a mutated creature called Swiggler. Swiggler was a strange creature used for powering up The Shroobs spaceships, by drinking vim, then powering the ships attached to a long cord on it's rear.