Robert Henry Rimmer (March 14, 1917 – August 1, 2001) was an American writer who authored several books, most notably The Harrad Experiment, which was made into a film in 1973.

The recurring theme in almost all of Rimmer's writing was a criticism of the assumption of monogamy as a societal norm. They explore various ways of organizing life, through laws or other means, to facilitate non-monogamous relationships.