Erdmonas Simonaitis (October 30, 1888 in Juschka-Spötzen (Spiečiai), Province of East Prussia – February 24, 1969 in Weinheim, West Germany) was a Prussian Lithuanian activist particularly active in the Klaipėda Region (Memel Territory) and advocating its union with Lithuania. During the staged Klaipėda Revolt of 1923, he headed the pro-Lithuanian government of the region. For his anti-German activities, he was persecuted by the Nazis during World War II.