Question: Was the Joker an enemy of the Avengers?, Answer:No, Description of Joker (character): Fictional character in the DC Universe, Fact1: The Joker is a DC Comics villain., Fact2: The Avengers are a group of heroes from Marvel Comics., Fact3: Being from different publishers, they do not meet.
Step1: Which world does the Joker exist in?, Step2: The Avengers are from which universe?, Step3: Is #1 the same as #2?, Wikipedia page for step 1: The Joker (DC), Wikipedia page for step 2: Avengers (MCU), Wikipedia page for step 3: , not_definitive_answer: False, incorrect_answer: False