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.

Trivia

 * Brobot's name is a portmanteau of "bro" (a shortened word for "brother", referring 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.
 * Mr. L calls Brobot his "Metal Bro."