Joker (voiced by Mark Hamill) is Batman's arch enemy and a villain in Gotham City and one of the villains in Pooh's Adventures of Batman: Mask of the Phantasm. When the Joker discovered that the Phantasm who iced the old gang like Salvatore Valestra, Chuckie Sol and Buzz Bronski, he began to plan to kill the Phantasm and rule Gotham, but Batman and Pooh and his friends stopped Joker and saved Gotham.
- Joker came back with his girlfriend, Harley Quinn along with Two-Face and The Penguin to get revenge on Pooh and his friends in Winnie the Pooh Goes to Atlantis: The Lost Empire.
- Joker and Harley returned in Pooh's Adventures of Teenage Mutant Ninja Turtles and Pooh's Adventures of Teenage Mutant Ninja Turtles 2: The Secret of The Ooze where they worked with The Shredder.
- Joker and Harley appeared in the Bonus ending of Pooh's Adventures of Home on the Range.
- Joker and Harley recently returned in Pooh's Adventures of 101 Dalmatians where they worked with Cruella De Vil along with Jafar, Iago, Maleficent, Ursula, Hades, and The Grand Duke of Owls.
- Joker will become the member with Two-Face, The Penguin, and The Fearsome Five as The Crime Empire.
- Joker will get his revenge on Ash and his friends in Ash's Adventures of Batman: Mask of the Phantasm.
- Joker will become Littlefoot's enemy in Littlefoot's Adventures of Batman: Mask of the Phantasm.
- Joker will become Bloom's enemy in Bloom's Adventures of Batman: Mask of the Phantasm.
- Joker and Harley will team up with Scar, Shenzi, Banzai, Ed, The Grand Duke of Owls, Jessie, James, and Meowth of Team Rocket to work for King Jareth in Ash Ketchum Goes to Labyrinth.