Pierre-Hubert Nysten (30 October 1771 – 3 March 1818) was a French physiologist and pediatrician who was a native of Liège.
Shortly before his death, he attained the position of médecin-chef at the Hospice des Enfants Assistés (children's hospital) in Paris.
With Xavier Bichat (1771–1802), Nysten performed pioneer experiments in cardiology, including studies involving the effects of galvanic current on the heart.
In 1805 he studied silkworm diseases in southern France, and provided an early description of polyhedrosis.
The eponymous "Nysten's Law" defines the progressive states of cadaveric rigidity during rigor mortis.