Master

The Master is a fictional character in the U.S. television series Buffy the Vampire Slayer, played by Mark Metcalf. He also made two cameo appearances in the spin-off Angel.

The Master first appears in "Welcome to the Hellmouth", the first episode of Buffy, as Buffy's first Big Bad. The Master is the ruler of the Order of Aurelius, a vampire cult which has included the likes of Darla, Luke and The Three, amongst many others.

The Master came to Sunnydale seeking to open the town's infamous hellmouth.

The Master is known to have been very old. He sired Darla, who is the sire of Angel.

Trivia

 * Joss Whedon's notes for the pilot indicate that the Master's name was Heinrich Joseph Nest and his age was 600 years. However, the flashback to 1609 in the episode "Darla" shows the Master already with his bat-like demonic visage, meaning he was far older than just 600 years by 1997, as this would have made the Master just 200 by 1609.
 * The Master was originally supposed to have a beard and long hair. Mark Metcalf came up with the bald, more demonic look as an homage to Nosferatu.