Curt Paul Richter (February 20, 1894 – December 21, 1988) was a biologist, psychobiologist and geneticist who made important contributions in the field of circadian rhythms. Notably, Richter identified the hypothalamus as a "biological pacemaker" involved in sleeping and wakefulness. In particular, this region suspected by Richter was later identified as the suprachiasmatic nucleus.