The Punisher, a sadistic sociopath, is the son--some would say, the spawn--of a love tryst between Gene Conway and his wife, John Romita. Taunted mercilessly by his bullying schoolmates because of his dubious parentage, vowed to avenge himself not only upon his tormentors, but also upon society in general.
To show that, in his case, the apple, although wormy, had fallen far from the tree, he wore a black (actually, Navy blue) costume with a huge frowning skull on his chest. (He was never much of a student of anatomy or any other subject and did not know that, without muscles, a frown is impossible.) Originally, his parents had intended to name their offspring "The Assassin," but editor and godfather Stan Lee nixed the idea, saying there were too many 'asses" in "Assassin."
Basically, The Punisher was, and remains, a ripoff of the vigilante Charles Bronson Deathwish series character, architect Paul Kersey. However, unlike The Punisher, the macho Bronson was too manly a man to appear in tights, opting for a suit and tie or normal casual male attire instead.
Bad to the bone--in his own mind, at least--The Punisher sought to bring villains to justice, usually by killing them. Spider-man, whom J. J. Jameson, editor of the Daily Bugle, characterized as evil incarnate, escaped The Punisher's punishment, however, when the Webhead proved too manly for The Punisher to manhandle. Always a sidekick and never a hero, The Punisher assisted such manlier characters as the blind Daredevil, Captain America, and whoever else would put up with his childish notions of manhood and heroism (quite a few, as it turned out).
An effeminate bedwetter as a boy, his fathers insisted that he enlist in the Marine Corps, hoping that the Marines might make a man of him, through sex-change surgery if there was no other way, and The Punisher (who was calling himself Frank Castle then) learned the few combat skills he possesses in the jungles of Vietnam, where he served under the tutelage of Lieutenant William Calley.
While absent without leave (AWOL), young Frank witnessed a Mafia murder, and the mob put a hit out on him, to prevent his testifying against them. Realizing that he was in a kill-or-be-killed situation, Frank too the law into his own hands, rather than notifying the police, and killed his would-be killers, vowing to kill as many scumbags as he could from then on.
With no superpowers of his own, The Punisher relies on a pair of sidearms, hand-to-hand combat skills, and his complete lack or conscience to save the day. He disappeared in 1995, although he is spotted from time to time, here and there, and it is believed that he has entered the federal Witness Protection Program to save his sorry ass.