in Batman: Under the Red Hood John DiMaggio was what fictional supervillain created by Bill Finger
Joker (character) The Joker is a fictional supervillain created by Bill Finger, Bob Kane, and Jerry Robinson who first appeared in the debut issue of the comic book "Batman" (April 25, 1940), published by DC Comics. Credit for the Joker's creation is disputed; Kane and Robinson claimed responsibility for the Joker's design, while acknowledging Finger's writing contribution. Although the Joker was planned to be killed off during his initial appearance, he was spared by editorial intervention, allowing the character to endure as the archenemy of the superhero Batman.
Detective Chimp Detective Chimp (alias Bobo T. Chimpanzee) is a fictional comic book character appearing in books published by DC Comics. A common chimpanzee who wears a deerstalker hat (à la Sherlock Holmes), Detective Chimp has human-level intelligence and solves crimes, often with the help of the Bureau of Amplified Animals, a group of intelligent animals that also includes Rex the Wonder Dog. He was originally created in the final years of the Golden Age of Comic Books, during the interregnum between the former and the Silver Age of Comic Books.