Erasmus Morgan Weaver Jr. (May 23, 1854 – November 13, 1920) was a United States Army major general who served as the first chief of the Militia Bureau and the Chief of the Army's Coast Artillery Corps.

He graduated from the United States Military Academy in 1875 and received his commission as a second lieutenant of Artillery.

[5][6] In 1898, Weaver was appointed to the temporary grade of lieutenant colonel of the 5th Massachusetts Infantry, a volunteer regiment raised during the Spanish–American War.

[7][8] From 1908 to 1911, Weaver served as a head of the Army's Militia Bureau, he was the first person to hold the position.

[9] Weaver was the Chief of the Coast Artillery Corps from 1911 until his retirement in 1918, when he was succeeded by Frank W. Coe.