He has the biggest direct bodycount, but the fact Cartman still terrorized the world and basically purged cities with Cthulhu menas he still has him beat, in case you forgot.
It is easy to gloss over too, but basically half of the kids are borderline supers, from the top of my head:
Stan was the host of Satan.
Cartman got a unnatural degree of charisma and can shoot lightning (SoT showed he still has the V-Chip).
Kyle is All-Jew,Half-Jersey Half-Crabpeople.
Ike is Jewel thief master hacker playboy.
Kenny is Immortal and a Japanese Princess
Craig got ancient Peruvian powers and "Gay powers".
Jimmy is "Actually Fast" and can Ad-sense.
Timmy is a Rockstar Timetraveller.
Butters brings death where he goes and got the strongest imagination in the world.
Im probably forgetting shit too.