(born 1938), U.S. basketball player. Known as the Big O, Oscar Robertson was long considered the best all-around player in National Basketball Association (NBA) history. A graduate of the University of Cincinnati, he began his professional career as a guard with the Cincinnati Royals in 1960. He was traded to the Milwaukee Bucks in 1970 and, with Kareem Abdul-Jabbar, won four Midwest division titles for the Bucks, as well as the NBA championship in 1971. He made the all-star team each year from 1961 to 1974 and held the NBA league record for assists in a career (9,887) until 1991. (See also Basketball.)