Magneuris Sierra (born April 7, 1996) is a Dominican professional baseball outfielder for the Acereros de Monclova of the Mexican League.

In 2014, he was the Cardinals Minor League Player of the Year after batting .386 with a .939 on-base plus slugging percentage (OPS).

Because of injuries to José Martínez, Stephen Piscotty, and Dexter Fowler, the Cardinals called Sierra up to the majors on May 7, 2017, and started him in center field the same day in a 6−4 extra innings victory versus the Atlanta Braves.

[6] His first major league hit was a single in the sixth inning of his debut versus starting pitcher R. A.

[9] On December 14, 2017, the Cardinals traded Sierra, along with Sandy Alcántara, Zac Gallen, and Daniel Castano, to the Miami Marlins for Marcell Ozuna.

[12] Sierra spent most of the 2019 season split between the Triple-A New Orleans Baby Cakes and the Double-A Jacksonville Jumbo Shrimp, but did appear in 15 major league games, notching a .350/.381/.425 batting line with 1 RBI.

[17] He would go on to score the decisive run on a Taylor Ward sacrifice fly in the tenth inning as the Angels won 4–3.

He would later express frustration about being so close but missing out on the potential walk-off home run, saying, "I've always dreamed of having a walkoff homer.

In a game on September 6, in which Sierra entered as a pinch-runner, he came to bat in the bottom of the 10th inning tied 4–4 with runners at first and third and one out.

[27] On April 22, 2024, Sierra signed with the Hagerstown Flying Boxcars of the Atlantic League of Professional Baseball.