André-Louis Debierne (French pronunciation: ​[ɑ̃dʁe lwi dəbjɛʁn]; 14 July 1874 – 31 August 1949) was a French chemist and is considered the discoverer of the element actinium. Debierne studied at the elite École supérieure de physique et de chimie industrielles de la ville de Paris (ESPCI ParisTech). He was a student of Charles Friedel, was a close friend of Pierre and Marie Curie and was associated with their work. In 1899, he discovered the radioactive element actinium, as a result of continuing the work with pitchblende that the Curies had initiated.