7. Dan Severn
The Beast starts off the list as being one of the first competitors to make mainstream cross-over appearances between MMA and Professional Wrestling. Severn was an All American Amateur wrestler in college and a U.S. Olympic alternate, but gained notoriety in the MMA at UFC 4 by being the first man to fight Royce Gracie to a fight well beyond the 6 minute mark. He is also the only man to hold both a UFC and Pro Wrestling Championship at the same time as he was NWA Champion and UFC Super Fight Champion in 1995. As NWA Champion, Severn was brought in during the Attitude Era of WWE as part of an angle that featured an NWA Invasion. He was put into a program with UFC rival Ken Shamrock as Vince McMahon began a flirtation with using MMA fighters for his promotion. Severn arrived with an in-ring performance that heavily contrasted most of the other matches featured on the card. He employed the use of multiple suplexes, palm strikes, takedowns, and relentless ground and pound on all of his opponents. As a result, his matches had an edgier, realistic, but subdued feel to them. While his character and ring presence fit in well with the rougher side of the Attitude culture, Severns straight-laced persona didnt quite flourish with the flamboyance of the product. Even still, Severns featured performances in the WWE acted as a trial period for the implementation of MMA and grappling techniques to be used predominantly in a professional wrestling performance. A Brawl for All Shoot Tournament was even implemented to try to establish wrestlers on the active roster as legitimately tough. Unfortunately, the tournament was ill-received by fans at the time and nobody got over in the end. Severn would continue to work in both MMA and professional wrestling, still competing to this day.