Kyle Brofoloski, a character from South Park.
Key-per, a character from Adventure time.
K-9, a character from Looney Tunes.
King of Theives from Adventure Time.
Kitara from Avatar
Kanga and eyore and piglet and poo
Kenny from South Park.
KenshiroKankuroKitty White (Hello Kitty's name)
kanga from Winnie the pooh and kid notorious and the kool-aid man
Well... Kermit the Frog?? I guess he's not exactly a cartoon though... Kit, of the Kit 'n' Carlyle cartoon strip
naruto
TAZ
Olive Oyl is a character in the Popeye cartoon. It begins with the letter O.
Yosemite Sam is a cartoon character. He is in Looney Tunes cartoons.
Zelda
Naruto