Lorraine Lois Foster (December 25, 1938, Culver City, California) is an American mathematician.

In 1964 she became the first woman to receive a Ph.D. in mathematics from California Institute of Technology.

Born Lorraine Lois Turnbull, she attended Occidental College where she majored in physics.

She was admitted to Caltech after receiving a Woodrow Wilson Foundation fellowship.

In 1964 she joined the faculty of California State University, Northridge.