Ken Shamrock 
Shamrock was known as “The World’s Most Dangerous Man”, and it’s a moniker that he earned by beating it out of his opponents. Before Shamrock ever stepped foot into a WWF ring, he trained for mixed martial arts and professional wrestling in Japan’s Fujiwara Gumi, where he gained a submission win in 45 seconds! He was part of a group that created a promotion called Pancrase, which combined all different types of fighting into one sport, with the exception of closed-fist punches to the head. At the very first show, Shamrock defeated his mentor and friend, Masakatsu Funaki, in the main event.
Once he left Pancrase for the UFC (his record in Pancrase being 17-3), he defeated Patrick Smith in his first UFC bout. He then had a feud with Royce Gracie, which began after Shamrock was defeated by Gracie. The feud finally came to a fight for the UFC Championship at UFC 5, which was saddled with a 30 minute time limit and ended in a draw. Fans have been rallying for a rematch ever since, but it never came to pass. Instead, Shamrock defeated his future long-time foe, Dan Severn, for the UFC Superfight Championship, in a match he won in a little over 2 minutes.
In 1997, Shamrock left the UFC for the WWF, seemingly at the top of his game. He was widely regarded as the best fighter in the world, so his signing to the WWF was a huge deal for both parties. Shamrock would go on to become the WWE Intercontinental Champion, one half of the WWE World Tag Team Champions (w/ Big Bossman), and the 1998 King Of The Ring, a title which he defeated The Rock to win!