Even in 2015, there's still something mysterious about The Undertaker. Many have hailed Mark Calaway's alter ego as the greatest gimmick the WWF/WWE have ever come up with. It's hard to argue with that point, given the fact that 'Taker has been around pretty much constantly since debuting in 1990. Much like his storyline brother, Kane, Undertaker's back story has been toyed with greatly. At first, the gimmick was simple. Appearing as an undead zombie of sorts, Undertaker was then controlled by the contents of an urn clutched by his portly manager, Paul Bearer. A rebirth of sorts was experienced for the character in the mid-90's, and Calaway started to show more of his actual wrestling ability as time wore on. Quickening the pace of his matches proved crucial in keeping The Undertaker relevant. Evolving once more into an infernal overlord, Undertaker was the leader of the 'Ministry Of Darkness' in the late-90's. A short sabbatical was followed by a more realistic approach. Becoming the 'American Bad Ass', 'Taker acted more like a normal human being, and fans were even told he had a life outside of wrestling. Nowadays, he's a unique character, one who simply exists as a legend in WWE. Calaway has managed to constantly tweak his character without sacrificing intrigue or mystery, which he deserves a lot of credit for.