John Hartman (born March 18, 1950) is an American drummer who was a co-founder and original drummer of the Doobie Brothers. At the band's inception, Hartman was the sole drummer. However, in late 1971, the group added second drummer Michael Hossack, and the dual-drummers formation has persisted ever since. (Hossack was replaced in 1973 by Keith Knudsen.)
Hartman played on all of the Doobie Brothers' major hits of the 1970s with both Tom Johnston and Michael McDonald. He left early in 1979 following a promotional tour in support of the award-winning Minute by Minute album to look after Arabian horses on his California ranch.
Hartman was enticed to join twelve Doobies alumni (including drummers Hossack, Knudsen, and Hartman's own 1979 replacement Chet McCracken) for a brief benefit tour in 1987. Hartman subsequently rejoined when the band was reconstituted the following year. He played on the reunion albums Cycles (1989) and Brotherhood (1991) as well as the accompanying promotional tours. However, following a 1992 alumni reunion for the benefit of terminally ill percussionistBobby LaKind, Hartman retired permanently from the band. In typical Doobies fashion, he was replaced by his former partner, Keith Knudsen.