Colin Sinclair (born December 19, 1994) is an American tennis player representing the Northern Mariana Islands. He achieved a career best singles ranking of world No. 340 on 18 September 2023 and a doubles ranking of No. 200 on 10 April 2023.
Sinclair has won four ATP Challenger and eight ITF Tour doubles titles. Additionally, he has won three singles ITF titles. He represents the Northern Mariana Islands in Davis Cup as part of the Pacific Oceania team since 2017 and has a career record of 18–5 (13–3 in singles, 5–2 in doubles) in the competition.