What about the Gump from Return to Oz?
You could call him Gumpy!
umm… a seasick cuckold?
Yagot (Yoda and Gumby on trombone)
Balrog.
Just don’t turn off all the lights.
DAMMIT! That was mine!
In that case, I suggest Dread Davoromu, the Destroyer, Scourge of Worlds, Devourer of Maidens, and Head Patissier.
A moldy rhino.
Kermit.
Now, excuse me, I’ve got to go wash off this pork smell. 
Jealousy
Call him Lrrr.
Grendel.
The Wuggly Ump.
Well, he doesn’t have horns, but he’s green and lizardy: Elliot (aka Pete’s Dragon)
A greenhorn.
As I recall, there was a spinoff series of a human character set in Pal-ul-Don who rode one particular triceratops, which had a name. Anyone remember this besides me?
The Sons of Erin Drum & Bugle Corps.
Reep Daggle (Chameleon Boy from the Legion of Super Heroes).
He’s not always green, is he? He could be red or even blue, no?
Aahz from Robert Asprin’s Myth series
Green Manalishi?