List of Famous people who are 21

Jon Callas is an American computer security expert, software engineer, user experience designer, and technologist who is the co-founder and former CTO of the global encrypted communications service Silent Circle. He has held major positions at Digital Equipment Corporation, Apple, PGP, and Entrust, and is considered "one of the most respected and well-known names in the mobile security industry." Callas is credited with creating several Internet Engineering Task Force (IETF) standards, including OpenPGP, DKIM, and ZRTP, which he wrote. Prior to his work at Entrust, he was Chief Technical Officer and co-founder of PGP Corporation and the former Chief Technical Officer of Entrust.

R. Christopher White is a two time Oscar-nominated visual effects artist.

Karl John is a Swiss orienteering competitor. He received an individual silver medal at the 1970 World Orienteering Championships, and a silver medal in relay in 1972.

Mark Seibert is an American musician, composer, and producer best known for his work on various video games from Sierra Entertainment.

John Leveque is a sound editor. He has won two BAFTAs for sound and has been nominated by the Motion Picture Sound Editors for sound.

Jeong Na-eun is a South Korean badminton player affiliated with Hwasun County team. In her junior, she won a bronze medal at the 2018 World Junior Championships and a silver at the Asian Junior Championships with her partner Wang Chan.