Also notable for an odd compulsion: Whenever he hears any part of the song Come Sail Away by Styx, he has to finish it. Typically he tries to get this over with as quickly as possible, however it also became a track of South Park's Chef Aid album, where it's given that unique "Cartman" twist.
In all seriousness, Cartman is the classic "dirty little bastard" type (literally; his parentage is unknown, as it turns out his mother is actually his father and s/he doesn't remember who the mother is). Possibly the most beloved character in the series, but mostly because people just love to see him in pain (which happens quite frequently).