Gummi Bears.
Ducktales.
Talespin.
Darkwing Duck.
Goof Troop.
The Real Ghostbusters.
Sonic (SatAM) - Don't confuse it with the other lame 1993 Sonic cartoon.
David the Gnome.
Chip'N'Dale, Rescue Rangers.
He-Man and the Masters of the Universe.
She-Ra.
Voltron.
Teenage Mutant Ninja Turtles.
The Snorks.
Inspector Gadget.
Underdog.
Rocky and Bullwinkle.
Scooby Doo.
A Pup Named Scooby Doo.
The Smurfs.
Garfield and Friends.
Heathcliff. <== Kicks Garfield's @ss.
Dennis the Menace.
Alvin and the Chipmunks.
Chipmunks go to the Movies. <== Batmunk owns all.
Angry Beavers.
Futurama.
Jabberjaw. <== Cartoon Network Groovies!
Batman.
X-Men.
Spiderman.
Johnny Quest.
Added by others.
Mighty Max. *Thanks to bobobologna*
Aaaaah! Real Monsters! *Thanks to pichu_pichu*
Hey Arnold! *Thanks to pichu_pichu*
Rocko's Modern Life. *Thanks to pichu_pichu*
Rugrats. *Thanks to pichu_pichu*
Johnny Bravo. *Thanks to pichu_pichu*
Dexter's Laboratory. *Thanks to pichu_pichu*
GI Joe. *Thanks to bobobologna*
Denver the Last Dinosaur. *Thanks to bobobologna*
Tiny Toons. *Thanks to bobobologna*
Captain Planet. *Thanks to bobobologna*
Jetsons. *Thanks to bobobologna*
Flintstones. *Thanks to bobobologna*
Transformers. *Thanks to bobobologna*
Cadillacs and Dinosaurs. *Thanks to trestres*
James Bond Junior. *Thanks to trestres*
Space Ghost. *Thanks to trestres*
Catdog. *Thanks to trestres*
Aladdin. *Thanks to trestres*
Charlie Brown and Snoopy Show. *Thanks to trestres*
I'm not including anime (Robotech, Thundercats...etc) in my list. ^_^
Edit: ssj12 says that Voltron is an anime and not a cartoon. Well I say screw that. Voltron is awesome and this list would not be complete without it.
Also, 80s cartoons were awesome.