Batman is a superhero who appears in American comic books published by DC Comics. Batman was created by writer Bill Finger and artist Bob Kane, and debuted in the 27th issue of the comic book Detective Comics on March 30, 1939. In the DC Universe, Batman is the alias of Bruce Wayne, a wealthy American playboy, philanthropist, and industrialist who resides in the fictional Gotham City. Originally a millionaire, the character is later depicted as a billionaire. As Batman, he vows never to kill any criminal. His origin story features him swearing vengeance against criminals after witnessing the murder of his parents, Thomas and Martha, as a child, a vendetta tempered by the ideal of justice. Vowing never to use firearms and other lethal weaponry, he trains himself physically and intellectually, crafts a bat-inspired persona and arsenal, utilizes his family wealth and resources, and monitors the Gotham streets at night. Kane, Finger, and other creators accompanied Batman with supporting characters, including his sidekicks Robin and Batgirl; allies Alfred Pennyworth and James Gordon; love interest and occasional adversary Catwoman; as well as foes such as the Penguin, the Riddler, Two-Face, and his archenemy, the Joker.