Sofia Vladimirovna Vassilieva (born October 22, 1992) is an American actress who played Eloise in Eloise at the Plaza and Eloise at Christmastime and Jenna Polly in the ABC TV show Notorious, Roxy Bental in the CBS/ABC Studios TV show Criminal Minds: Beyond Borders, as well as portraying Ariel DuBois in the NBC/CBS drama series Medium from 2005 to 2011.