Joker

Ace is Batman's pet dog during the Golden Age. He is a member of the Batman Family but has made no appearance since No Man's Land.

Alfred Thaddeus Crane Pennyworth is Bruce Wayne's (Batman's) Butler. He is one of the very few people who know that Batman is Bruce Wayne.

The man who would break the bat got his start in a Peña Duro prison where he was injected with the venom serum. Bane unleashed waves of villains to weaken Batman and is known for breaking his back. In the future he is in a hospital still being pumped with venom.

Cassandra Cain is the latest to don the Batgirl mantle. At the cost of her voice she was trained to be a lethal fighter by reading her opponents movements. Her actions do speak louder than her words.

Anyone will tell you-Joker is the most dangerous and demented villian in all of Batman's foes. He is totally crazy, and has committed every crime in the book. He's murdered over 500 people-in a single week. He was responsible for Jason Todd death brutally beating him. He shot the original Batgirl, Barbara Gordon, in the spine, paralyzing her. And overall has put Gotham through more hell then anyone else. Batman's stopped him on numerous occasions, and he gets carted back off to Arkham-before returning with a vengeance on Gotham City.

while Batzarro's possible creator, Batzarro foild Joker's attempt to kill Batman.

The maniacal Joker is Batman's most dangerous foe. Unpredictable, murderous and surprisingly cunning, the Joker is a threat to both heroes and villains alike.

Humiliated in his own time-period (the 25th century), Michael Jon Carter steals future technology and a security robot named Skeets, and travels back into the 20th century to become Booster Gold.

Gorilla Grodd is a super-intelligent telepathic gorilla. He is often an opponent of The Flash

Green Arrow fought the joker several times when he was on JLA.

Guy Gardner fought the joker several times when he was on JLA.

Hawkman fought the joker several times when he was on JLA.

Helena Bertinelli is a superheroine modelled after Batman. She employs gadgets similar to his and has even gone by the name of Batgirl at some point.

Joker murdered Iron Cross.

The joker killed Jason Todd's mother and severely beat him to death and later left Todd to die in an explosion.

The maniacal Joker is Batman's most dangerous foe. Unpredictable, murderous and surprisingly cunning, the Joker is a threat to both heroes and villains alike.

In a not-too-distant future, the Joker goes to the Daily Planet and kills over 90 people, including Lois Lane. He was soon found and killed by Magog.

Former member of the Blackhawks, now the pilot for Oracle's Birds of Prey.

DUPE

J'onn J'onnz was teleported to Earth from Mars and stranded here 50 years ago. He now uses his extraordinary Martian abilities as the Martian Manhunter, and has been a faithful member of every incarnation of the Justice League.

Mr. Mxyzptlk has access to fifth-dimensional technology that to third-dimensional beings may as well be magic. He can perform any feat imaginable. If he wished he could turn Superman into dust by snapping his fingers, it would happen. However, he's not actually malevolent like most villains, so he uses his powers doing things that are more annoying than anything else.

The maniacal Joker is Batman's most dangerous foe. Unpredictable, murderous and surprisingly cunning, the Joker is a threat to both heroes and villains alike.

The maniacal Joker is Batman's most dangerous foe. Unpredictable, murderous and surprisingly cunning, the Joker is a threat to both heroes and villains alike.

Plastic Man fought the joker several times when he was on JLA.

The maniacal Joker is Batman's most dangerous foe. Unpredictable, murderous and surprisingly cunning, the Joker is a threat to both heroes and villains alike. The Joker kills Psimon during Salvation Run with a fatal blow to the head with a rock.