Lissa

Lissa was a demon allied with the First Evil.

Knowing that dark times were due to come, Lissa decided to ally herself with the First Evil and do her part by preforming a ritual sacrifice in order to raise a Turok-Han Vampire. Adopting the guise of a beautiful woman, Lissa met Xander Harris while shopping for rope to use in the ritual (although she told Xander that the rope was for use in storing her kayak). Lissa and Xander later went on a date to the Espresso Pump, which culminated in her taking Xander back to Sunnydale High School where she attempted to use him as her ritual sacrifice by bleeding him over the Seal of Danzalthar.

Although she stabbed Xander and bled him on the Seal, her plans were thwarted by Buffy Summers, Robin Wood and Spike who came to Xander's rescue. Only a Turok-Han's arm got through before being severed by the closing Seal, and Buffy decapitated Lissa, who reverted fully to her demonic form in death.