Of course. A lot of them! Anderson Silva, Overeem, Hunt, Cro Cop, Barbosa, Shogun etc. MMA fighers usually come from 3 backgrounds: wrestling, Muay Thay, BJJ. There are also some boxers and Judo fighters but still those 3 are the most important.
anyone mention Cosmo Alexandre, he just started in MMA last year won the kings cup torunement in 2009 many think he should have won it again the next year losing to yodsanklai by a close decision. His MMA career hasnt gone too well so far but its still early, probably the best Muaythai fighter I know of from brazil. He signed to bellator last year winning his first fight there by tko. [ame]http://www.youtube.com/watch?v=oLnYlcWdY5A[/ame]
good fighter strong in the clinch. had a competitive fight with Petro, probably would have won it under FTR ( the ref separated the clinch right away, seemed Cosmo was stronger there).