Martin Viiask (born 27 April 1983 in Tartu, Estonia) is a former Estonian professional basketball player. Viiask started his senior club career in 2000 in Ehitustööriist. In the next year signed with Tartu Ülikool/Rock and played there until 2007, when he signed with Estonian rival Kalev/Cramo. He has also played for Kuremaa and TTÜ. His last season was with Tartu Ülikool/Rock on 2009–2010. He has also been a member of the Estonia national basketball team. Currently he works as a real estate broker in Tartu.