Dr. Gill Gilliam is a snail disease expert, and snail expert.
His first and only appearance is in the season 4 episode "Once Bitten." He looks almost exactly like the Purple Doctorfish, though he's orange, and the purple doctorfish is purple. He appears when everyone panics in the Krusty Krab about having Mad Snail Disease. He then explains to everyone that he is a S.D.E and as well a S.E (snail disease expert and snail expert). Then he tells them that there is no such thing as Mad Snail Disease and that it is only just a myth. To prove his point, he takes the "small" splinter out of Gary's foot which ends curing Grouchy Snailitis (though Gary still bites Mr. Krabs buttocks).
Appearance
He is an orange fish who wears a white buttoned coat and glasses. He has green lips and (unlike many fish in the show) he has arms and fingers just like SpongeBob.