A musician and singer-songwriter, born in Ontario, Canada.

Spence was a guitarist in an early line-up of Quicksilver Messenger Service before Marty Balin got him to be the drummer for Jefferson Airplane. After recording one album with Jefferson Airplane, their debut Takes Off, he left to co-found Moby Grape, once again as a guitarist.

Spence suffered from schizophrenia. During the 1968 recording of the group's second album, Wow, Spence allegedly attempted to break down a bandmate's hotel room door with a fire axe while on LSD and was committed for six months to the criminal ward at New York's Bellevue Hospital.

Upon his release, he recorded his only solo album, the now-classic psychedelic/folk album Oar (1969, Columbia Records). However, mental illness and alcoholism prevented him from sustaining a career in the music industry and he lived much of his later life as a homeless person in Santa Cruz, California. When it finally seemed that he might have been overcoming those afflictions, lung cancer claimed him in 1999 at the age of 52.

Spence continued to have minor involvement in later Moby Grape projects and reunions.