René Kalmer (born 3 November 1980 in Roodepoort, Gauteng) is a female South African runner who has competed over distances ranging from 800 metres to the marathon.
She represented South Africa at the 2008 Summer Olympics, running in the 1500 metres.
She then represented South Africa again at the 2012 Summer Olympics, competing in the marathon.
She is a two-time participant at the World Championships in Athletics (2001 and 2011) and has run at eight editions of the IAAF World Cross Country Championships.
Her sister, Christine Kalmer, is also an international level runner.