The clown named Pennywise is sometimes referred to by the title of the movie 'It'. The Invisible Man also starts with I if you disregard the 'The'.
Kim Possible.
'character' is another name for 'letter' in this case.
X-Men
yuffie
Eeyore
TAILS
goofy
Ignatz the cat.
verminous
you mean the letter U? UnderDog
Krazy Kat.
ROAD RUNNER.
Homer Simpson
Nemo
TiggerTazTom Cat
kangaroo jack