Peter Nils Sundelin (born 13 January 1947) is a retired Swedish sailor. Together with his elder brothers Jörgen and Ulf he won a gold medal in the 5.5 metre class at the 1968 Olympics and a silver medal at the 1969 World Championships. The brothers also won the 1971 world title in the three-person keelboat (Dragon class) and placed sixth and ninth at the 1972 and 1976 Olympics, respectively. Peter was the strongest physically among the Sundelin brothers. In the 1980s, he competed with different partners in the two-person keelboat at the 1980 Olympics and world championships. Besides sailing he played ice hockey for Skuru IK.