A churl is a rude or nasty person. The basketball player who's constantly jabbing opponents with his elbows and deliberately tripping them is a churl.
Churl comes from the Old English ceorl, "peasant," and originally that's exactly what it meant: a commoner, or person who didn't belong to the nobility. During the 15th century, the word became somewhat negative, meaning "a low fellow," and by the 1800s it meant "person inclined to loutish behavior." Today churl is less common than its related adjective churlish, but it's still a great name for someone who's vulgar and mean.