There’s to be a new FBI agent hunting aliens on “The X-Files.” Annabeth Gish, 29, will join the Sunday Fox drama in a three-episode arc this season with an option to return in the fall as a regular on the show, Hollywood trade papers are reporting. The Albuquerque native first made a splash when she costarred with another newcomer, Julia Roberts, in the 1988 movie “Mystic Pizza.” So far, Gish’s character on “X-Files” does not have a name, but she will be brought to the team by agent John Doggett (Robert Patrick, 41) from the New Orleans office, where she has been investigating satanic cults, series creator Chris Carter told the Hollywood Reporter. “She is quite unlike any of the other agents,” he said. “She has been neither a firm believer nor a major skeptic, either.” Gish’s character also has some personal history with Doggett, who requests her help in a case involving agent Fox Mulder (David Duchovny, 40). Her first episode, which is set to air Feb. 25, will also mark Duchovny’s return to the series this season.