Gwen Lieber (Tanit Phoenix) was a villainess from Lost Boys: The Thirst (2010). She was an author of vampire novels who approached Edgar Frog regarding her missing brother, Peter, suspecting that he was taken by vampires. Edgar turns Gwen down at first, but he later appears at Gwen's place and accepts her offer, while also voicing his displeasure over her novels. Gwen brings along Lars Van Goetz, a former reality TV star hoping to use the mission to save his career.
Peter is saved from DJ X, who is believed to be the vampire alpha holding him hostage, and he is reunited with Gwen. Edgar, Alan, and the rest of the group quickly realize that Gwen and Peter are not siblings when they see the pair making out with each other passionately, and at that moment, Gwen turned heel and revealed her true role as a co-conspirator with the real alpha: Peter. Gwen's plan was to bring Edgar to Peter, who plan to turn him into his personal vampire hitman to keep subordinate vampires in line. Regarding her motive, the evil Gwen stated that she wanted to become a vampire herself, but instead of that, Peter simply killed Gwen by ripping her throat out.