"Presumably Marvel Comics' anti-hero Deadpool derived his name from Clint Eastwood's final Dirty Harry movie, The Dead Pool (1988). But Eastwood's Harry Callahan is a police officer who harshly metes out justice and is a man of severe demeanor and few words. Deadpool, on the other hand, is a mercenary who operates outside the law and has a manic personality, continually rattling off stream-of-consciousness repartee. In this respect Deadpool is like an outlaw Spider-Man on speed, and they even wear similar costumes. Deadpool is often called 'the Merc with a Mouth."
"Created by artist Rob Liefeld and scripter Fabian Nicienza in New Mutants #98 (1991), Deadpool was originally presented as a villain who battled Cable, the original X-Force, and Wolverine. Probably due to his wild sense of humor and panache, Deadpool became so popular that he starred in his own comics miniseries (Deadpool: The Circle Chase, 1993, and Deadpool, 1994), and graduated to his own villain who evolves into a hero, or, in his case, anti-hero with emotional depth beneath his banter. Though he remained an outlaw, Deadpool's stories pit him against considerably more evil opponents."