<P> Reed Birney portrays Mr. Prescott in seasons one and two, a teacher at Constance Billard and St. Judes . Jill Flint portrays Bex Simon in seasons one and two, Lily's art dealer and a minor love interest for Rufus . Alison Humphrey, Rufus' ex-wife and Dan and Jenny's mother is portrayed in season one by Susie Misner . Mädchen Amick portrays Duchess Catherine Beaton in the second season . She has a short affair with Nate . Her stepson, Lord Marcus Beaton is portrayed by Patrick Heusinger in season two . He has a relationship with Blair . At first he pretends to be a college student called James, but when Blair thinks he is boring, he tells her the truth . When Blair finds out that he is having an affair with his stepmother, she blackmails them into leaving the country . Tamara Feldman portrayed Poppy Lifton in the second and sixth seasons, a friend of Serena's . Her boyfriend, Gabriel Edwards, is portrayed by Armie Hammer in the second season . When Serena comes back from a holiday in Spain with Poppy and Gabriel, she starts a relationship with him . However Poppy and Gabriel are actually still together and use Serena to steal money from Lily . John Patrick Amedori portrays Aaron Rose in season two, an artist who becomes a love interest for Serena . However she leaves him when she realizes she still likes Dan . Willa Holland portrays Agnes Andrews in season two and for one episode in season three . She is a model that befriends Jenny, however when the two become business partners, things go wrong and they become enemies . Andrew Tyler, a detective that works for Bart and Chuck, is portrayed by Kevin Stapleton in seasons two and four . Aaron Schwartz portrays Vanya in seasons two, three and four, the doorman at the building of LIly's apartment, who later marries Dorota . He and Dorota have a daughter in season three and a son in season five . Laura Breckenridge plays Rachel Carr, Dan's romantic love interest and his teacher in Season - 2 </P> <P> Joanna Garcia portrays Bree Buckley in the first four episodes of season three . Her and Nate's families are rivals and they begin a "Romeo and Juliet" kind of relationship . When she finds out that her cousin is left at the altar at her wedding to Carter Baizen, she tries to get revenge on him for her family, which leads to her and Nate's break - up . Olivia Burke is portrayed by Hilary Duff in season three . She is a famous movie star that starts a relationship with Dan . They break up when she realizes Dan has feelings for Vanessa . Deanna Russo portrays K.C. Cunningham, Olivia Burke's publicist and Serena's former boss, in season three and for one episode in season four . Laura Harring portrays Elizabeth Fisher in season three . She's Chuck's mother, who was thought to have died when giving birth to Chuck . She reveals to Chuck that she left when he was born, because she was nineteen and had no intentions of marrying Bart . Bart later paid her to stay away from their son . She also dated Chuck's uncle Jack in the past, who she gave Chuck's company to after he had given it to her . Sherri Saum portrays Holland Kemble in season three . She is hired by William van der Woodsen to seduce Rufus in order to break up him and Lily . Luke Kleintank portrays Elliot Leichter, Eric's bisexual love interest, in seasons three and four . Jessica, portrayed by Alice Callahan in seasons three, four and five, is one of Blair's new minions at Columbia . </P> <P> Clémence Poésy portrays Eva Coupeau in the first four episodes of season four . She saved Chuck from dying when he was shot in Prague . They start a relationship and she changes Chuck into a better more philanthropic person . When Blair tries to break them up, she finds out that Eva was a prostitute, but Chuck forgives Eva for not telling him and dedicates a charity in Eva's name . However Eva dumps Chuck when, after all the good things she has done for him, Chuck is still duped by one of Blaire's devious schemes into thinking Eva was only using him . Chuck realizes the error only too late as Eva, heartbroken at Chuck's distrust, flies back to France . Dean Reuther, the dean of Columbia, is portrayed by Jayne Atkinson in season four . Samuel Page portrays Colin Forrester in season four, Juliet's cousin and Serena's college teacher, who she has a short relationship with . Carol Rhodes, portrayed by Sheila Kelley in seasons four and five, is Lily's sister who comes to New York with Ivy, who pretends to be her daughter Charlie, in order to get access to Charlie's trust fund . Brian J. Smith portrays Max Harding in season five, Ivy's ex-boyfriend, who finds out that she is pretending to be someone else and blackmails her . Jane, portrayed by Michael Michele in season five, is a movie producer that hires Serena, but she soon quits . Marina Squerciati portrays Alessandra Steele in season five, a publicist that publishes Dan's book . </P> <P> During season five, Roxane Mesquida portrays Béatrice Grimaldi, Louis' sister who doesn't approve of her brother's interest in Blair . Marc Menard portrays Father Cavalia, a priest from Monaco with ties to Blair's fiancé, Louis . Amanda Perez as Tina, Nate's assistant at The Spectator . </P>

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