Although born in the United States, she grew up in Norway and made her debut, aged eight, on Norwegian television.
Proctor is a graduate of Harvard University, where she played Nina in Anton Chekhov's The Seagull. She went on to appear opposite Debra Winger in an American Repertory Theatre production of Ivanov. She has performed on stage in Dublin, Oslo, London, New York, Boston and Los Angeles.
Proctor's first film role was in The men in my life with Drew Barrymore. She has subsequently appeared in TV shows such as CSI: NY, Numb3rs, NCIS, All My Children and played the character Aimee on the HBO series The Wire.