Joachim ("Aki") Rademacher (20 June 1906 – 21 October 1970) was a German water polo player who competed in the 1928 Summer Olympics and in the 1932 Summer Olympics. He was born in Magdeburg. In 1928 he was part of the German team which won the gold medal. He played all three matches and scored two goals. Four years later he won the silver medal with the German team. He played all four matches. His older brother Erich was his teammate in both tournaments. He also competed in swimming, winning the bronze medal in the men's 1500 m freestyle at the first European Championships in 1926, and the gold in the men's 4×200 m freestyle relay event.