Spacey was born in South Orange, New Jersey, the son of Kathleen Ann (née Knutson; December 5, 1931 – March 19, 2003), a secretary, and Thomas Geoffrey Fowler (June 4, 1924 – December 24, 1992), a technical writer and data consultant. He has two older siblings: a sister, Julie, and a brother, Randy. He has Swedish (from his maternal grandfather), English, and Welsh ancestry. Spacey attended Northridge Military Academy, Canoga Park High School (in tenth and eleventh grades), and then Chatsworth High School inChatsworth, Los Angeles, where he graduated valedictorian of his class. At Chatsworth High, he starred in the school's senior production of The Sound of Music, playing the part of Captain Georg von Trapp, opposite Mare Winningham's character, Maria.
While in high school, Spacey took on his paternal grandmother's maiden name, "Spacey," as his acting surname. Several reports have incorrectly suggested that he took his name in tribute to actor Spencer Tracy, combining Tracy's first and last names. He had tried to succeed as a comedian for several years, before attending the Juilliard School in New York City, where he studied drama, between 1979 and 1981. During this time period, Spacey performed stand-up comedy in bowling alley talent contests.