Rupert Giles comes from a family of Watchers - both his father and grandmother also served in that capacity - and he was told at a young age that he too would become one, which disappointed him since he had plans either to be a fighter pilot or a greengrocer. He attended Oxford University, where one of his friends, Carlyle Ferris, fought a She-Mantis, losing both the battle and his sanity.

Giles eventually rejected the family destiny and dropped out of Oxford, choosing instead to dabble in the Occult - he and five friends summoned a demon named Eyghon. Only two of that group - Giles and Ethan Rayne - still survive, the others having been killed by the demon. Although he is no longer the practitioner he was in his youth, his skills in spellmaking have proved useful on more than one occasion.

He was the curator at a museum in England, possibly the British Museum, prior to being assigned as Buffy's Watcher. He also plays the guitar, although he is a little rusty (see 2.8 - "The Dark Age"), is multilingual, has some skill in fencing and shooting a tranquiliser gun, and lists cross-referencing among his favourite hobbies.

Giles is the librarian at Sunnydale High School. It is presumed that he has a master's degree in library science or the British equivalent in order to qualify for his current position. It is also presumed that Principal Flutie gave him broad discretion in choosing the contents of the library, since it includes several ancient texts that would seem out of place in an ordinary school library, but which are extremely useful when he needs information to help Buffy and the Slayerettes fight the demons of Sunnydale.

Aside from Jenny Calendar and the late Dr. Gregory, his relationships with his fellow faculty members are not common knowledge. He dated Jenny for sometime, although the possession of Jenny by the demon Eyghon set things back a bit, as did the truth about her Romany background and the reason why she came to Sunnydale, although they had been making some headway towards a reconciliation when she was murdered by Angelus (see 2.17 - "Passion").

Giles is well-read and intelligent, can play the guitar, fence, and read five languages — and, if necessary, he can hold his own in a fight. Giles has always been straight-laced and stereotypically British, but he has loosened up a bit since he was fired from his post as Watcher (after interfering with the Council's rite of passage test for Buffy). Giles is currently a man of leisure (read: unemployed), and doesn't seem completely comfortable with that fact. His unemployment has, however, given him time to develop his talent for singing and playing guitar — he's even performed at the Espresso Pump.

Giles is played by Anthony Stewart Head.