A character from Torchwood and some episodes of Doctor who. He is played by John Barrowman. He often fights Aliens from outer space. He has the inability to die, yet still ages. Some theories suggest that he is the younger version of The Face Of Boe.
Captain Jack Harkness can kick Captain Jack Sparrows ass!
A fun way to say "Oh my God" Some people find it annoying, which makes it even more fun to use. Some people feel it's using the lords name in vain, but as you can clearly see it's spelled gawd, not god, so no, it's not taking his name in vain.