The Riddler is a Batman villain who first appeared in Detective Comics #140 in 1948. He is an enemy of Batman and is known for his use of riddles and puzzles to challenge the Dark Knight. He is one of Batman's most enduring foes and has been featured in various media, including television series, video games, and films. The Riddler is a master criminal who uses his intellect and knowledge of puzzles to commit crimes. He is often portrayed as a genius-level intellect with a penchant for wordplay and riddles.