Sinclair Greenwell Jr. (December 1935 - July 7, 1992) was an American jazz alto saxophonist.
Sinclair Greenwell was born in December 1935 in Fort Worth, Texas.
At Lafayette Junior High School he practiced Charlie Parker solos and met pianist Horace Tapscott.
Greenwell and Tapscott formed a band with trumpeter Roy Brewster and drummer Charles Pendergraff while they attended Jefferson High School.
Greenwell was a founding member of Tapscott's Pan Afrikan Peoples Arkestra in 1961 and played in the group until the mid-1980s.