Léon Dacheux (2 March 1835, in Bischheim – 8 March 1903, in Strasbourg) was an Alsatian Catholic clergyman and historian.
He studied the classics at the Petit Séminaire and theology at the Grand Séminaire in Strasbourg, being ordained as a priest in 1857.
In 1859 he attained the chair of rhetoric at the Petit Séminaire, and from 1868 onward, he served as a pastor in Neudorf-Strasbourg.
In 1881 he was named supérieur at the Grand Séminaire, and in 1887 was appointed chanoine titulaire at the Cathédrale Notre-Dame de Strasbourg.