From his biography, Sid Haig was born in the city of Fresno in the state of California and he was raised in the Armenian Community. The father is Haig Mosesian and worked as an electrician. He became an actor by accident. While growing up, he had a rapid growth which was interfered by the motor coordination and this made him to take up the dancing lessons. When he was 7 years, he got paid as a dancer while in the Christmas show of children and afterwards, he joined Vaudeville revival show.

Sid Haig showed the musical talent and mostly with drums and this made his parents to get a drum set for him. On the set he was able to master many types of the music including Rock and Roll, Blues, Jazz, Country and Swing. He was able to earn money using his music and he signed the recording contract of one year after high school. While he was still a teenager, he recorded a single under the name of Full House with T-Birds. It reached the number 4 at Billboard Charts.

While in high school, Alice Merrill was a head of the drama department and he encouraged him to go into acting. She was an actress at Broadway and maintained the contacts in this business. In the senior year, there was a play that was produced where Merrill was doubling the cast and wanted her friends in Hollywood to come and assess the ability of the actors to choose the final players.

Sid Haig was among the chosen few and she was seen by Dennis Morgan who is a big musical comedy star of 1940s and he chose him to have a prominent role in that play. After the play, he told him to continue acting like a career and to continue the education at San Fernando. After two years, he joined Pasadena Playhouse where other actors like Dustin Hoffman, Gene Hackman and Robert Preston had trained.

Sid Haig is known for the baritone voice and the shaved head. He is married and his wife is Susan L Oberg. She is also known in the film industry. He got married at the age of 68. At the age of 75, he scared people when he got hospitalized because of illness.