[Skulhedface]

They used to have Hey Arnold comic strips in the short-lived Simpsons magazines.

Oh, and to stay on-topic:

Masters of the Universe
The Real Ghostbusters
Teenage Mutant Ninja Turtles
Transformers (the old stuff, not this Beast Wars bullshit)
Thundercats
Super Mario Bros. Super Show
early Nicktoons AND Cartoon Network cartoons
Tom and Jerry
Count Duckula
Inspector Gadget