Judith Guest (March 29, 1936) is an American novelist and screenwriter. Born in Detroit, Michigan, she is the great-niece of Michigan Poet Laureate Edgar Guest (1881-1959).

She graduated from Dondero High School in Royal Oak in 1954, then studied English and psychology at the University of Michigan, graduating with a BA in education. She taught at a public school for a number of years before making the decision to devote herself full time to completing a novel.

Her first book, Ordinary People, published in 1976, was made into a 1980 film that won the Academy Award for Best Picture. This novel and two others, Second Heaven (1982) and Errands (1997), are about adolescent children forced to deal with a crisis in their family. She also wrote the screenplay for the 1987 film Rachel River.

Guest co-authored the mystery Killing Time in St. Cloud (1988) with fellow novelist Rebecca Hill. Guest's most recent book, The Tarnished Eye (2004), is loosely based on a true unsolved crime in her native Michigan.

She is married to a businessman named Larry Lavercombe and has lived in Edina, Minnesota, since 1975. She is a resident of Harrisville, Michigan.