Calvyn Justus (born 14 December 1995) is a South African swimmer. He competed in the men's 4 × 200 metre freestyle relay event at the 2016 Summer Olympics. He is an alumnus of Westville Boys' High School. In 2018, Justus placed third in the 4x100 medley relay at the Commonwealth Games, along with teammates Chad Le Clos, Cameron van der Burgh and Brad Tandy.