Shaun Paul Cassidy (born September 27, 1958 in Los Angeles, California) is an American singer, actor and TV producer and writer.

The oldest of three sons born to Shirley Jones and Broadway entertainer/television star Jack Cassidy, he first found success as a teen idol, following in the footsteps of his elder half-brother, David Cassidy of TV's The Partridge Family. He went to Beverly Hills High School.

Shaun was born on September 27, 1958, and traveled with his parents when he was only six months old while they were doing shows. His parents were stage and screen actors Shirley Jones (I) and Jack Cassidy (I) who were both heavily involved in the business. When he was a pre-teen, he started a band called "Every Mothers Dream" and when his mother and half-brother, David Cassidy (I), were both starring in a musical TV sitcom called "Partridge Family, The" (1970), he asked his mom to put him in some episodes. However, she refused as she wanted to encourage him to concentrate on his schooling. He did appear as part of the chorus in many musical theatre productions. In 1972, he then sang in a punk rock band called "The Longfellow," which was short-lived, as his parents transferred him to a private school in Beverly Hills. He had a chance to star with his mother as James Preston in a summer stock stage musical production of "On A Clear Day You Can See Forever" to get a taste of acting. During his grad year, he decided to make some records in Germany and had a hit there called "Morning Girl" and appeared in TV shows with his hit there as well as in Australia. Then, in late 1976, he signed up with agent Ruth Aarons and played Christopher Wentworth Hewlitt in a short independent film called Born of Water (1976) and successfully auditioned for the role of Joe Hardy in "Hardy Boys/Nancy Drew Mysteries, The" (1977). Also, he had a dream of becoming a writer and re-wrote some of the scripts of the series to make it more suitable for him, which angered the producers of the show. On an episode of the show, he sang some numbers as his character in a local disco, which led to a number of hit 45s and albums. In the 1980s, he made acting a primarily focus after his role in the movie of the week titled Like Normal People (1979) (TV) which he was well credited in as the mentally challenged Roger Meyers as well as playing Dave Stohler in the short-lived series "Breaking Away" (1980)_ based on the popular motion picture, which only 8 episodes were produced due to a writers strike. He then decided to learn the true craft of acting and pursued it on stage by starring in such productions like "Mass Appeal," "The Subject Was Roses," "Diary of a Hunger Strike," "Dangerous Music," "Pass/Fail," and "Blood Brothers" with Petula Clark and his half-brother David Cassidy (I) -- in their first show together. After a few more TV guest roles, movies of the week as well as acting on stage, he pursued his dreams as was mentioned and retired from acting to produce and write TV shows and films, including the short-lived but well-acclaimed "American Gothic" (1995) as well as the other TV series "Agency, The" (2001) and "Invasion" (2005). He also write the sequel to the hit motion picture Midnight Run (1988) titled Midnight Run for Your Life (1994) (TV), which became a noted TV movie. Writing and producing became Cassidy's most successful career in the industry today like for many other celebrities like former actor Ron Howard (I). He admitted to this day he was only half good as a singer and admitted he had some limitations as an actor and felt he didn't enjoy it enough to pursue for the rest of his life.