Patrick Brett O'Sullivan (August 11, 1887 – November 10, 1978) was a U.S. Representative from Connecticut.

Born in Derby, Connecticut, O'Sullivan attended public schools.

He served as judge of the Connecticut Superior Court from 1931 to 1950, associate justice of Connecticut Supreme Court 1950-1957, and chief justice in 1957, serving from April 9 to August 11 of that year, when he reached the mandatory retirement age.

He was interred in St. Lawrence Cemetery, West Haven, Connecticut.

This article incorporates public domain material from the Biographical Directory of the United States Congress