About Borko Bariæ Expertise I am a big fan of NBA basketball, especially its history, so I have pretty good knowledge of the past players, teams and stats.
Experience You should have asked me 5 years ago. I was a real nut back then... :)
Well, that's pretty difficult to answer. I haven't found any exact data, but my guess would be it was George Mikan. I'm not 100% sure he invented it, but I know that that was one of the signs of his overwhelming dominance during the late 1940s and early 1950s.
I do know that, in NCAA basketball, dunking was forbidden for a few years, mostly due to Lew Alcindor's (later Kareem Abdul-Jabbar) unstoppability. And dunking as an "art form" was more or less invented by Julius Erving, aka Dr. J.