Brobot

Brobot is Mr. L's gigantic robot in Super Paper Mario. He is created to be shaped like Luigi's head. After Mr. L loses to Mario and his team in combat, Mr. L summons his giant robotic brother and fights Mario's team in a battle oddly similar to scrolling space shooters such as Gradius. Once he loses, Mr. L vows to face Mario again. He has kept his promise, for he comes back in Chapter 6-1, after Sammer's Kingdom gets destroyed by The Void. His new improved Brobot L-Type has arms and legs this time and is more powerful, able to swallow Mario and fire rocket punches at him. However, Mario uses Boomer to destroy Brobot once and for all.

Trivia

 * Brobot's name is a portmanteau of "bro" (a shortened word for "brother", refering to Luigi) and "robot".
 * Interestingly, the name "Brobot" was previously applied to a recurring character on the television program The Adventures of Jimmy Neutron: Boy Genius, although the two characters' names are likely coincidental; the aforementioned portmanteau isn't so creative.
 * Super Dimentio looks like Brobot, but is not mechanical.