A: Arnold, from Hey Arnold!
B: Bender, from Futurama
C: CatDog, from CatDog
D: Dexter and Didi, from Dexter's Laboratory
E: Eustace, from Courage the Cowardly Dog
F: Ms Frizzle, from The Magic School Bus
G: Gogo Dodo, from Tiny Toon Adventures
H: Heffer Wolfe, from Rocko's Modern Life
I: Ickis, from Aaahh!!! Real Monsters