Ruy Tadeu Aquino de Oliveira (born 1 February 1953) is a former international freestyle swimmer from Brazil, who competed at one Summer Olympics for his native country. He was at the 1971 Pan American Games, in Cali, where he won two bronze medals, in the 4×100-metre freestyle and in the 4×200-metre freestyle, both breaking the South American record. He also finished 7th in the 100-metre freestyle. He was the South American record holder of the 100-metre freestyle, between 1972 and 1980.