Oswaldo Carlos Blanco Díaz (born September 8, 1945) is a former Major League Baseball first baseman. He batted and threw right-handed.
Blanco posted a .196 batting average in 52 games for the Chicago White Sox in 1970 and the Cleveland Indians in 1974. He was traded along with José Ortiz by the White Sox to the Chicago Cubs for Dave Lemonds, Roe Skidmore and Pat Jacquez on November 30, 1970.
In 2015, he was enshrined into the Venezuelan Baseball Hall of Fame and Museum.