#2 Kane - 23 years
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While Triple H and Kane may have entered the company in the same year, Kane pipped The Game to the post by a few months. Of course, he didn't enter the company under the moniker of 'Kane', and it took him a few years before he really burst into life - but that doesn't mean we can't appreciate the fact that this man has spent more than two decades of his life with WWE.
He is the definition of a company man and while his career has certainly experienced some highs and lows, he's still going to go down in history as an all-time legend in professional wrestling. Sure, he's off focusing on the world of politics right now, but he'll likely be back for another short run before eventually riding off into the sunset.