Anya

-- Emma Caulfield interview (with BBC)
-- Emma Caulfield interview (with BBC)

Anyanka is about 1,120 years old. After her boyfriend betrayed her ( the Troll in the episode “Triangle”), she was granted magic powers by the demon D’hoffryn, in the form of an immortal vengeance demon. She became the Patron saint of scorned women.

In 1998, Anyanka arrives in Sunnydale, to avenge Cordelia Chase, whose boyfriend (Xander Harris) cheated on her with his best friend, Willow Rosenberg. Cordelia doesn’t know who or what 'Anya' is, and ingenuously wishes in front of her, that Buffy Summers had never come to Sunnydale; believing this mess was all Buffy's fault. Anyanka makes Cordelia's wish come true, and sends her to a parallel dimension where Sunnydale is ruled by Vampires (which both Xander and Willow happen to be).

After working out the situation, Cordelia tries to explain it to Giles. However, before she can convince him, she is killed. Giles manages to do some research on Anyaka and discovers that in order to break the spell, Anyanka's amulet must be destroyed, which he ultimately does. The amulet contained the source of all of Anyanka’s powers, and after being destroyed, Anyanka loses it, together with her immortality, effectively becoming 'human' again.

Anya hasn’t yet customized with being a human again. She behaves very strangely around the Scooby gang, because she doesn't know how to act socially, or tries to fit in, but doesn't. What scares her most is growing old and dying (next to rabbits), after being immortal for over a 11 centuries, it is difficult to get use to the idea. Her greatest quality has to be her sincerity, but sometimes being so sincere, in the real world, might be a defect. Although at first, the gang didn't quite get along with Anya, recently she has become a regular and fits in nicely, although Willow still has her doubts. Anya and Xander have been going out since the end of Season 3, which has helped in her quest for fitting in and acceptance from the rest of the group. It is no doubt that her wittiness, charm and complete honesty are what make her so hilarious.

Curious Facts: Did you know that Anya is terrified of bunnies? She also met Dracula quite a long time ago and found him 'very charming'. She often likes to reminisce on the incredible way she tortured men when she was a demon. In Season 4, she was afraid of being captured by the The Initiative, she was very skeptical of Riley’s friends.