Marie Masters (born Marie Mastruserio; February 4, 1941) is an American actress, writer, and director. She is known for playing the role of Dr. Susan Stewart on the CBS Daytime soap opera As the World Turns (1968 to 1979, 1986 to 2010). She also worked as a staff writer on ATWT, beginning in 2001. She has directed theatrical productions and worked as an assistant director on Broadway shows. She was the assistant artistic director for The New Group, a nonprofit theater company.