Frank Grimes, Jr.

Frank Grimes Jr. is the main antagonist of the 2002 The Simpsons episode The Great Louse Detective. He is the son of Frank Grimes and an enemy of Homer Simpson who wants to avenge his father. He

History
After Homer Simpson is subject to several murder attempts, Sideshow Bob is roped in to help him find the perpetrator, who is revealed to be Junior, Homer's mechanic. No one knew of his true lineage until he revealed it to them upon being cornered, he is Frank Grimes Jr., the illegitimate child of Frank Grimes, Homer's old power plant co-worker from the episode Homer's Enemy. His dad "happened to like hookers", and one of them gave birth to him. The real reason behind his intent to kill Homer was because he believed that Homer killed his father by driving him insane when Grimes Sr. accidentally killed himself by electrocuting himself while imitating Homer. He also becomes more infuriated in each passing moment he shares with Homer, just like his father. He has yet to reappear in future episodes.

In the story in Simpsons Comics #125, Homer was framed by Mr. Burns for dealing nuclear weapons and arrested. He was cellmates with Sideshow Bob, who ironically was the man who helped Homer defeat him, and they escaped from jail by going through a tunnel in a cell occupied by a masked prisoner. The three fell into Mr. Burns' secret lair, where the mysterious prisoner was revealed to be Grimes. Sideshow Bob then fell on him and both were knocked unconscious. Homer was cleared of his charges while Bob and Grimes were arrested and sent back to prison.