On March 1st 1896 Henri Becquerel discovered spontaneous radioactivity.
Henri Becquerel was born on 15th December 1852 in Paris, France. He was born into a family of distinguished scientists.
For his discovery of spontaneous radioactivity Becquerel was awarded half of the Nobel Prize for Physics in 1903, the other half being given to Pierre and Marie Curie for their study of the Becquerel radiation. Henri Becquerel
He died on on August 25, 1908.
You can read more about him here: Henri Becquerel and the Serendipitous Discovery of Radioactivity