Ubiratan Pereira Maciel (January 18, 1944 – July 17, 2002) was a basketball player from Brazil. He is often regarded as the greatest Brazilian center of all time. He was born in São Paulo, Brazil. He was nicknamed "O Rei" (English: "The King").
Maciel won the top-tier level club league in Brazil, the Brazilian Basketball Championship, 5 times, in the years 1965, 1966, 1969, 1977, and 1981.
Maciel won a total of 8 medals at the Summer Olympic Games, FIBA World Championship, and Pan American Games.
Maciel was named one of FIBA's 50 Greatest Players in 1991.
In 2009, he was inducted into the FIBA Hall of Fame, as a player. On April 5, 2010, Maciel was announced as a member of the 2010 induction class of the Naismith Memorial Basketball Hall of Fame, as a player, and was formally inducted on August 13.