Monica Julieta Reyes (b. March 13, 1968, Austin, Texas, USA) is a fictional character on the TV series The X-Files, played by actress Annabeth Gish. She appeared in the opening credits of Season 9, although her first appearances were in season 8.

Monica Reyes was given up for adoption as a child, adopted by Mexican parents and raised in Mexico, having never identified her biological parents. Because of growing up in Mexico, Reyes speaks fluent Spanish.

She majored in folklore and mythology at Brown University, earning her bachelors and masters degrees in four years. In 1990, Reyes enrolled to the FBI at Quantico in 1990. Her first assignment in the FBI was serving on a special task force investigating Satanic rituals.

Reyes then served in the New York City field office, and also investigated the kidnapping of 8 year-old Luke Doggett, son of New York City police officer John Doggett. The boy was eventually found dead, but no suspect was ever apprehended. In 1999, Monica Reyes transferred to the New Orleans field office. She remained there until John Dogget, now an FBI agent, convinced her to accept a post on the X-Files FBI unit in Washington, DC, as his partner.

Monica Reyes is religious and a highly spiritual person, and has little doubt about the paranormal. She is not as obsessed with it as Fox Mulder is, but she is willing to accept explanations involving the paranormal, unlike John Dogget.