Léon Daum (21 March 1887 – 28 May 1966) was a French mining engineer, company director and senior European administrator.

Jean Daum became a master glass maker in 1876, and from 1878 was the owner of the Fonderies de Nancy.

Léon's parents were Jean Louis Auguste Daum (1853–1909) and Jeanne Constantin (d. 1921).

Léon was cited by the Corps des mines for the devotion and technical wisdom he applied to the perilous work of assisting the victims.

In May 1921 he joined the Compagnie des forges et aciéries de la marine et d'Homécourt as chief engineer.

[1] In 1923 Daum participated in the Inter-Allied Mission for Control of Factories and Mines (MICUM) during the occupation of the Ruhr.

[1] Léon Daum was one of the leaders of the Comité des forges, the French steelmaker's association.

[5] It was replaced by the Comité d'organisation de la sidérurgie (CORSID – Organizing Committee for the Iron and Steel Industry).

He facilitated the creation of Sidelor, and prepared the merger of Marine-Homécourt with the Aciéries de Saint-Etienne.

[9] At the request of Robert Schuman he agreed to become one of the first nine members of the European Coal and Steel Community (ECSC).

[3] He was expected to be an effective representative of French industrial interests, but in fact he took a detached long-term view and was soon the target of complaints of indifference from the steel associations.