Thomas Wayne and his wife Martha Wayne, being murdered by a mugger in front of his very eyes.
This drives him to fight crime in Gotham City as Batman.
Bruce is brought up in Wayne Manor and its wealthy splendor and leads a happy and privileged existence until the age of eight, when his parents are killed by a small-time criminal named Joe Chill on their way home from the movie theater.
Bruce Wayne swears an oath to rid the city of the evil that had taken his parents' lives.
During this time, butler Alfred arrives at Wayne Manor and after deducing the Dynamic Duo's secret identities joins their service.
After the introduction of DC Comics' multi-verse in the 1960s, it is retroactively established that stories from the Golden Age star the Earth-Two Batman, a character from a parallel world.
He engages in intense intellectual and physical training; however, he realizes that these skills alone would not be enough.
"Criminals are a superstitious and cowardly lot", Wayne remarks, "so my disguise must be able to strike terror into their hearts.
Batman became a popular character soon after his introduction, and eventually gained his own title, Batman.
The character made his first appearance in Detective Comics #27 (May, 1939). Witnessing the murder of his parents as a child leads him to train himself to physical and intellectual perfection and don a bat-themed costume in order to fight crime.