Ray Lewis.
The difference between Lewis and anyone else is that he's what, 36 or so, and still playing at an elite level. The man is playing just as good in 2011 as he did when he was in his prime. He hasn't even come close to losing a step, never gets hurt, and has been the heart, soul, and backbone of his franchise since the day he was drafted.
One of the greatest players in NFL history, without a doubt.