Here's the lyrics to the first song I thought of:

CASPER THE FRIENDLY GHOST

Casper, the friendly ghost,
The friendliest ghost you know.
Though grown-ups might
Look at him with fright,
The children all love him so.

He always says hello (Hello),
and he's really glad to meetcha.
Wherever he may go,
He's kind to every living creature.

Grown-ups don't understand
Why children love him the most.
But kids all know
That he loves them so,
Casper the friendly ghost.

http://www.lyricsondemand.com/tvthemes/casperlyrics.html

There's no information on this page about who wrote this song. That's a shame.