Antoine Henri Becquerel (December 15, 1852 – August 25, 1908) was a French physicist, Nobel laureate, and one of the discoverers of radioactivity.
Becquerel was born in Paris into a scientific family which, including him and his son, produced four generations of scientists. He studied science at the École Polytechnique and engineering the École des Ponts et Chaussées. In 1892 he became the third in his family to occupy the physics chair at the Muséum National d'Histoire Naturelle. In 1894 he became chief engineer in the Department of Bridges and Highways.
In 1896, Becquerel accidentally discovered radioactivity while investigating phosphorescence in uranium salts. In 1903 he shared the Nobel Prize in Physics with Pierre and Marie Curie "in recognition of the extraordinary services he has rendered by his discovery of spontaneous radioactivity".
In 1908, the year of his death, he was elected permanent secretary of the Académie des Sciences. He died at the age of 55 in Le Croisic.
The SI unit for radioactivity, the becquerel (Bq) is named after him.