Viola Cheptoo Lagat (born 13 March 1989) is a Kenyan middle-distance runner specialising in the 1500 metres. She competed at the 2015 World Championships, 2016 World Indoor Championships and 2016 Summer Olympics. She comes from a family of runners that includes sisters and Everlyne Lagat as well as brothers Robert Cheseret and Olympic medalist Bernard Lagat.