nemo
Noddy
Nemo
* Naruto
NEMO!
Easy, Nelson, the bully
There's a cartoon stating with "n" called Naruto....
Well... Kermit the Frog?? I guess he's not exactly a cartoon though... Kit, of the Kit 'n' Carlyle cartoon strip
Elmer Fudd Ed, Edd n Eddy.
Naruto (from the anime Naruto) and Nelson ( from The Simpsons)
There was a comic strip character named Nancy, her boyfriend was Sluggo.
You could use Ninja Turtles for cartoon characters. They begin with the letter N.