There are a various amount of answers, and it all depends on whether it is to be full name or just last name or just first name.
First Name Only:
Scrooge McDuck
Grandma Duck
Matilda McDuck
Bolivar
Morcego Vermelho
Double-O Duck (If hypens are accepted as not splitting up a name into two separate fragments.)
Achille Talon
Perdita
Cruella de Vil
Colonel (101 Dalmatians)
Aladdin
Maurice (Beauty and the Beast)
Lumiere (Beauty and the Beast)
Both Names:
General Snozzie
Total:
The King (Cars)
By no means is this list exhaustive just yet.
Olive Oyl is a character in the Popeye cartoon. It begins with the letter O.
Eeyore
Naruto
goofy
VOLDEMORT
Ignatz the cat.
hades
You could use Ninja Turtles for cartoon characters. They begin with the letter N.
you mean the letter U? UnderDog
abner Alley Oop
Krazy Kat.
ROAD RUNNER.