Who is (or was) the Greatest fighter of all time?

I always hear folks talk about who they think is the baddest dude on the planet or who they believe was the toughest, roughest mo-fo so low-down that the ground shook when he walked by. I’ve heard every name and every description imaginable. From the Biblical (Goliath, Samson and yes, Jesus Christ himself) to the fantastic (somebody actually said the Predator one time and I’ve heard Jason’s [of Friday the 13 fame] name more than once. But hey, for the sake of keeping this as close to reality as is possible, let’s try to stay on the planet and within the last century or two, please.

When I refer to a true “fighter”, I’m not taking it lightly. I look at age, level of ability, talent, natural and/or developed, improvisational ability, adaptability, strengths, weaknesses (if any) and confidence. All of these factors come into play when assessing a fighters ability against other fighters. Whether we’re talking about Genghis Khan or Jim Jefferies, it all comes into play.

Who was/is the one with the all the abilities above and beyond those of lesser men and why? Back it up with some solid evidence and convincing testimony based in reality. Is Bruce Lee still the Father of Mixed Martial Arts and the greatest specimen the world has ever seen? Or is the power and legend of the indestructible Mas Oyama the real deal? Or perhaps the young, limitless and indomitable Cassius Clay [Muhammad Ali] in his prime, was he truly untouchable?

Everybody has an opinion. I’m asking for yours, here’s your chance to be heard.