He looks a lot like the Purple Doctorfish and Dr. Gill Gilliam, except Dr. Gill is light olive green and wears a light blue uniform, instead of a white one, and a head mirror.
He is first mentioned when SpongeBob tells Patrick that he better come with SpongeBob to see is Dentist, Dr. Gill.
When SpongeBob and Patrick get to Dr. Gill's Office, SpongeBob mentions Dr. Gill by mentioning the office.
Soon, SpongeBob mentions Dr. Gill by mentioning that Debbie is Gr. Gill's hygienist.
Dr. Gill then says, "Do I hear SpongeBob?" SpongeBob greets Dr. Gill. SpongeBob tells Patrick that Dr. Gill makes sure that one does not have cavities.
Debbie and Dr. Gill enter the waiting room. SpongeBob, Debbie, and Dr. Gill take hands and dance in a circle, singing, "I brush and floss my teeth each day to ward away that tooth decay!"
Later, after Debbie does her job, Dr. Gill checks SpongeBob's teeth. He says that SpongeBob's teeth are healthy. He says that they will not know for sure until they check the x-rays. He then says that SpongeBob is a model patient. SpongeBob thanks Dr. Gill. SpongeBob tells Dr. Gill that Patrick has never been to the dentist before.
When it was Patrick's turn, Debbie and Dr. Gill look at Patrick's mouth. Dr. Gill tells his receptionist to cancel his appointments for the rest of the day because it will take awhile.
After cleaning Patrick's teeth, Dr. Gill finds out that the light box that they use to view the X-rays needs a new light bulb. He then tells SpongeBob and Patrick to go home and that he will call them tomorrow for the results as it will be fixed by then.
The next morning, Patrick mentions Dr. Gill when he mentions Dr. Gill's receptionist.
At SpongeBob's follow-up appointment, Dr. Gill greets SpongeBob and Patrick. He then looks at SpongeBob's x-rays. He starts to say something, but then realizes that the x-rays are not SpongeBob's and that his receptionist must have mixed SpongeBob and Patrick's x-rays up.
When SpongeBob got up out of the chair, SpongeBob, Debbie, Patrick, and Dr. Gill linked arms and started dancing merrily.
Debbie mentions Dr. Gill when Patrick is in the chair to get his cavities fixed.
After Patrick gets his teeth filled, Dr. Gill tells Patrick that he needs to floss his teeth every night and to brush then twice a day for at least two minutes each time. He also tells Patrick to come back in six months. He tells Patrick that he can have a toothbrush from his drawer.