With professional sports leagues implementing more stringent policies on on-field player conduct over the last few years, athletes' pockets are being hit (word to Ndamukong Suh) and fans are starting to complain about the lack of intensity in games. But while some athletic misbehavior can be regulated, the refs can't catch everything, which is why dirty players like Bill Laimbeer, Ulf Samuelsson, and Bill Romanowski were able to wreak havoc in their respective sports. But what actions really define a "dirty" player? Concussion-causing hits? Physical abuse of refs? Grabbing balls (ayo!)? Spitting? Biting? Stomping? After research, we found it's all of those things—and a bit more. From the NBA to figure skating, MMA to NASCAR, and all sports in between, check out our list of The 50 Dirtiest Athletes in Sports History. Enjoy the mayhem and brutality!