The toughest professional fighters in history include some of the fiercest and bravest boxers, MMA fighters, and even wrestlers who proved their strength and perseverance time and time again. These tough men are the types you'd love to have behind you in a dark alley or a bar fight, as well as the men who entertain us on pay-per-view fights in the ring and the octagon. We can argue all day about the best boxers, MMA fighters and wrestlers, but which professional fighter is the toughest of them all? Who is the toughest man in history? Vote up your favorite and add other tough guys below.

Despite also being known for their silly UFC fighter nicknames, because of the skill required to compete and the level of danger of the sport, a great argument can be made that mixed martial arts fighters are some of the toughest pro fighters around. Anderson Silva, Fedor Emelianenko, Antonio Rodrigo Nogueira, Dan Henderson and the great Chuck Liddell all lead that pack as some of the toughest MMA fighters and the hardest men in history.

Others would argue that boxers are the greatest fighters in history. Ukrainian heavyweight Wladimir Klitschko, the great welterweight Micky Ward, top puncher Earnie Shavers and Muhammad Ali are favorites in the boxing world as some of the toughest to enter the ring. Sure, some of the technical best boxers of all time are not on that list but remember, this is about the toughest fighters, not necessarily the best.

Professional wrestlers can be added to the mix despite being more entertainers than athletes. Regardless, they are required to be pretty darn tough to do their jobs. Stone Cold Steve Austin, Terry Funk, and Mike Foley are just a sampling of the WWF/WWE wrestlers that you wouldn't want to take on in a fight.

Each of these professional fighters dealt with different challenges and opponents as they competed in their respective sports. All of these pro fighters proved their toughness time and time again. To get knocked down once and get back in that ring takes a whole lot of courage, and these fighters did that over and over throughout their careers. If that isn't a measure of toughness, I'm not sure what is.