List of Famous people who are 21

Keith "K. K." Barrett is an American production designer known for his work on feature films by Spike Jonze and Sofia Coppola, among others.

Reginald Jordan Perry is an American professional basketball player for the Brooklyn Nets of the National Basketball Association (NBA), on a two-way contract with the Long Island Nets of the NBA G League. He played college basketball for the Mississippi State Bulldogs.

Lisa Lassek is an American film and television editor. In addition to her editing career, her credits include her role as an associate producer for the television series Firefly. She edited episodes for the sixth season of Buffy the Vampire Slayer, served as an assistant editor for Angel, and has edited various episodes of Firefly. Lassek is a frequent collaborator of Joss Whedon, having edited his first feature-length film Serenity and the Marvel Cinematic Universe films, The Avengers and Avengers: Age of Ultron. She has also collaborated with Drew Goddard, having edited his films The Cabin in the Woods and Bad Times at the El Royale.