Seth Gilliam was born in November 5, 1968 and now worked as an American actor. He is known for his HBO television roles, first as corrections officer-turned-prisoner Clayton Hughes on Oz, and later as Baltimore police detective promoted to Sergeant Ellis Carver on The Wire. In both of these series, he co-starred with Lance Reddick and J.D. Williams.
His feature film credits include Private Sugar Watkins in the 1997 action movie Starship Troopers. Gilliam also had a recurring role during the seventh season of The Cosby Show as Aaron Dexter, boyfriend of Erika Alexander's Pam, and appeared in the 18th episode of the seventh season of CSI: Miami ("Flight Risk").
He is currently playing the role of Dr. Deaton.
The Veterinarian (Dr. Deaton) is a recurring character in Teen Wolf and is played Seth Gilliam. He works at the Beacon Hills Animal Clinic where he is Scott McCall’s boss. He is aware of the existence of werewolves and seems to know quite a bit about them.
During the season one this character was in argument. It is only mentioned once in Season 1, by Stiles in Night School. While it apparently appeared as Dr. Deaton on the call sheets for the production it appeared in no official public sources that could be considered official canon for the show. It was mentioned in the Teen Wolf webcomic at MTV.com, but events and characters in that publication do not match what happened on the actual show and so are not, at this time, considered official canon.
Then at the start of filming for Season 2 the name "Deaton" was officially added to official character on the show. He has now been called "Alan" on screen but there is no official spelling available for his first name.
Sources: Wikipedia.com and Teenwolf.wikia.com