A jazz trio is a group of three jazz musicians, often a piano trio comprising a pianist, a double bass player and a drummer. The pianist is usually considered the leader of these trios, and trios are usually named after their pianist. Famous examples include the Bill Evans Trio with Scott LaFaro on bass and Paul Motian on drums; and the Vince Guaraldi trio, featuring Fred Marshall and Jerry Granelli. Some jazz trios include: The American group Medeski Martin & Wood offers an organ trio variation whereby the guitarist is replaced by a bassist (Chris Wood).