Tiemen Groen (born 6 July 1946) is a retired Dutch cyclist who won four consecutive world titles in the 4 km individual pursuit in 1964–1967; His sporting career began with DTS Zaandam. He finished fourth in this event at the 1964 Summer Olympics. He also won a silver medal in the team time trial at the 1966 UCI Road World Championships. He retired shortly after turning professional in 1967.