Classic Cartoons:
* Cleo (Scooby-Doo)
* Captain Caveman (Captain Caveman and the Teen Angels)
* Cosmo (The Fairly OddParents)
* Chuck Jones (Looney Tunes director)
* Count Duckula (Count Duckula)
* Crush (Finding Nemo)
Modern Cartoons:
* Carl (Up)
* Carl Wheezer (Jimmy Neutron)
* Cody (The Suite Life of Zack & Cody)
* Coraline (Coraline)
* Craig (Craig of the Creek)
* Cleo (The Amazing World of Gumball)
* Chuckie Finster (Rugrats)
* Cody (Total Drama)
* Clarence (Clarence)
Other:
* Charlie Brown (Peanuts)
* CatDog (CatDog)
* Cindy Bear (Yogi Bear)
* Courage (Courage the Cowardly Dog)
* Chucky (Child's Play)
This is just a small sample - there are many more cartoon characters with names starting with "C"! Let me know if you'd like me to focus on a particular cartoon genre, like Disney or Nickelodeon.