USS Little Brothers (SP-921) was a United States Navy tug in commission from 1917 to 1919.

Little Brothers was built as a commercial fishing vessel of the same name in 1910 by George Bishop at Patchogue, New York.

On 21 July 1917, the U.S. Navy chartered her from her owner, John C. Doxsee of Islip, New York, for use as a tug during World War I.

Assigned to the 3rd Naval District and based at New York City, Little Brothers was employed in carrying military supplies and ammunition for the rest of World War I and into 1919.

She operated in the East River, New York Harbor, Gravesend Bay, Jamaica Bay, and Long Island Sound.