Batman and Robin

Batman and Robin from Lego: Batman the Video Game

Bruce Wayne's parents were killed by a mugger. So Bruce while growing up learned fighting styles and became at the peak of human psychical perfection to become a dark avenger. When a bat went into Bruce's window, he thought it was an omen so he became a "bat": Batman! Unlike most heroes, he uses gadgets (based off of real science) instead of powers. Dick Grayson (Robin) became Batman sidekick, when his patents fell to their death during a trapeze act sabotage by protection-extortionists. He has fought bizarre foes as the Mad Hatter, the Joker, the Penguin, Bane, Catwoman, Man-Bat and Clayface, since 1939. Later Robin left Batman and became Nightwing. He has gone though changes. In fact Bat-Mite said on "Batman: the Brave and the Bold" to a fan questioning the tone of the show:

"Batman's rich history allows him to be interpreted in a multitude of ways. To be sure, this is a lighter incarnation, but it's certainly no less valid and true to the character's roots as the tortured avenger crying out for mommy and daddy. Beside those mutant bunnies look really scary!"

References:

http://en.wikipedia.org/wiki/Batman

http://en.wikipedia.org/wiki/List_of_Batman_Family_enemies#Supervillains_and_themed_criminals

Batman: the Brave and the Bold episode #19

http://farm3.static.flickr.com/2207/2187155312_a37ec0e821.jpg