The character of John Constantine was created because the artists wanted to draw Sting

Alan Moore, speaking about Steve Bissette and John Totleben:
One of those early notes was they both wanted to do a character that looked like Sting. I think DC is terrified that Sting will sue them, although Sting has seen the character and commented in Rolling Stone that he thought it was great. He was very flattered to have a comic character who looked like him, but DC gets nervous about these things. They started to eradicate all traces of references in the introduction of the early Swamp Thing books to John Constantine’s resemblance to Sting . But I can state categorically that the character only existed because Steve and John wanted to do a character that looked like Sting.

More Comic Book Urban Legends here.