SpongeBob SquarePants
The first episode, "Help Wanted", aired in 1999.
1. SpongeBob
2. Patrick
3. Mr Krabs
Arthur
The first episode, "Arthur's Eyes", aired in 1996.
4. Arthur
5. Francine
6. D.W.
The Simpsons
The first Simpsons episode, "Good Night", aired on The Tracey Ullman Show in 1987. That's 30 goddamn years ago!
7. Lisa Simpson
8. Bart Simpson
9. Homer Simpson
10. Marge
South Park
The South Park kids first made an appearance in the short film Jesus vs Frosty in 1992.
11. Cartman
12. Stan
13. Kyle
14. Kenny
Dora the Explorer
The first episode, "The Legend of the Big Red Chicken", aired in 2000.
15. Dora
Teenage Mutant Ninja Turtles
The first epsiode, "Turtle Tracks", aired way back in 1987.
16. The Turtles: Leonardo, Michaelangelo, Donatello, and Raphael
My Little Pony
The cartoon first aired in 1984, and the first episode was "Rescue at Midnight Castle". In 2017, the show My Little Pony: Friendship Is Magic is a big hit with the kids.
17. Moondancer
18. Twilight
19. Applejack
20. Charlie Brown
21. Snoopy
Family Guy
The very first episode, an unaired pilot, was made in 1998.