Lionel Désiré-Marie-René-François de Moustier (23 August 1817 – 5 February 1869) was a French diplomat and politician.

[1] On 10 March 1853 Lionel de Moustier was appointed minister plenipotentiary in Berlin, where he helped to ensure the neutrality of Prussia during the Crimean War.

[4] Moustier provided statistics that showed that Prussia was mobilizing a force that could readily defeat France's army on the Rhine.

In the Roman question he enforced the convention of 15 September and opposed the concessions proposed by General Luigi Federico Menabrea, Italian Prime Minister.

Speaking in Senate he responded to Cardinal de Bonnechose and to Baron Charles Dupin that the government would support the rights of the Pope as well as Italian unification.

Léonel was active in the Resistance during World War II, was captured by the Germans and died in 1945.