Arlen F. Gregorio (born 1931 in San Francisco, California, United States) is an American attorney, politician and commercial mediator. He was a member of the California State Senate from 1970 to 1978. As a Senator he chaired the Senate Health and Welfare Committee from 1979 to 1984 and was an elected member of the San Mateo County Board of Supervisors from 1979 to 1984. After leaving politics in 1985 he began a career in mediation.