Explain xkcd: It's 'cause you're dumb.
Hairy is a stick figure character in xkcd. The name is unofficial, used by explain xkcders to describe male characters with hair and no other distinguishing features.
Hairy is not a single character but a categorization of various one-time characters. One Hairy, a learning pickup artist, has appeared in two comics (1027 and 1178).
When Hairy comes up against Cueball or Black Hat, he is most likely to come off worse (as in 1210: I'm So Random, or the pickup artist Hairy). Hairy can also appear just to add some variation in a group (1261: Shake That), or as a kid (973: MTV Generation, 1176: Those Not Present).