Although originally introduced as Scott Tenorman's father in Season 5's Scott Tenorman Must Die, it was later revealed in the "200"/"201" saga that he was...in fact... Cartman's father.
Jack Tenorman (along with his wife) was killed by Farmer Denkins, as part of Cartman's notorious revenge plot in Scott Tenorman Must Die. Cartman then stole the bodies, put them in chili, and fed it to Scott Tenorman at the Chili Con Carnival.
So indirectly, Cartman killed his own father...and fed it to his half brother...
- Jack Tenorman played for the Denver Broncos.