Diomedes Antonio Olivo Maldonado (January 22, 1919 – February 15, 1977), nicknamed "Guayubin" for his hometown, was a Dominican professional baseball player and scout.

The left-handed pitcher appeared in 85 Major League Baseball games over all or part of three seasons between 1960 and 1963 for the Pittsburgh Pirates and St. Louis Cardinals.

[2] His age at the time of his MLB debut is the oldest with the exception of Satchel Paige in the post-World War II era.

[3] In his first game, he pitched two scoreless innings of relief against the Milwaukee Braves, allowing one hit (to eventual Hall of Famer Eddie Mathews) and two bases on balls.

He scouted for the Cardinals after retiring from the field, and later held a position in the Ministry of Sports in his native country until his death, from a heart attack, at age 58.