Barry Knapp Bostwick (born February 24, 1945) is an American actor and singer. He is known for playing Brad Majors in the 1975 cult classic The Rocky Horror Picture Show, replacing Peter Scolari as Mr. Tyler in the sitcom What I Like About You, and playing Mayor Randall Winston in the sitcom Spin City. He has also had considerable fame in musical theater.

Bostwick was born in San Mateo, California. He is the son of Betty (née Defendorf), a homemaker, and Henry "Bud" Bostwick, Jr., a city planner and actor. His only sibling, Henry "Pete" Bostwick, was killed in a car accident on June 20, 1973. Bostwick attended San Diego's United States International University in 1967, majoring in acting, got his start on the Hillbarn Theatre stage now located in Foster City, and worked for a time as a circus performer.

He replaced C.C. Courtney in the show Salvation. In 1972, Bostwick originated the role of bad boy Danny Zuko in the stage production of Grease, earning a Tony Award nomination for his performance. In 1975 he starred with Tim Curry and Susan Sarandon in the Rocky Horror Picture Show. He also won a Tony Award for his performance in the 1977 musical The Robber Bridegroom. From 1996 to 2002, Bostwick portrayed Randall Winston, the Mayor of New York City in the sitcom Spin City opposite Michael J. Fox and his successor, Charlie Sheen. In 2006 Bostwick landed a role replacing Peter Scolari as Mr. Tyler in the relatively unknown star vehicle sitcom for then sixteen-year-old Amanda Bynes What I Like About You.