José Roberto Diniz Aranha (born 2 February 1951 in São Paulo) is a former international freestyle swimmer from Brazil, who competed at two consecutive Summer Olympics for his native country, starting in 1968. Between 1968 and 1972, he went to live and train in the United States. At the 1967 Pan American Games, in Winnipeg, he swam the 400-metre freestyle, not reaching the finals. At the 1968 Summer Olympics, in Mexico City, he swam the 100-metre freestyle and the 4×100-metre medley (along with José Fiolo, João Costa Lima Neto and César Filardi), not reaching the finals.