Darla
Darla is one of the most important vampires in the mythology of the first season. She is a member of the Bretheren of Aurelius and is the first vampire we ever see in the show, she is also the first vampire to ever fight the Slayer. Darla is very disobedient and is the only one to get away with it with the Master. When Luke is killed she takes his place as the Master's primary acolyte. She appears next in the episode entitled Angel she and the "Three" are sent to kill the Slayer and fail. She kills the the others of the "Three" for the Master and then visits Angel. In her visit we find out that she and Angel were romantically involved and that she was the person who brought the Gypsy girl whose family placed a curse on Angel's soul to Angel. We also learn that Darla was Angel's sire. Darla hatches a plan to get Angel back with her and the Master. She thinks if she can get Angel to kill Buffy he will be evil again. She bites Buffy's mother in front of Angel (being the only vampire to ever bite one of Buffy's friends or family) framing him. In the long run her plan doesnt work and Angel ends up killing Darla. The Master mourns her death by saying that she was his favorite for 400 years. Darla was brought back to life by the law firm Wolfram and Hart as a human to keep Angel busy. She could only live for awhile though, so Angel tried to help her stay alive, but his hopes were dashed when Drusilla sired Darla. Darla and Drusilla are now on a rampage and they wiped out all the share holders of Wolfram and Hart. Darla is played by Julie Benz.