USS Merrimack, or variant spelling USS Merrimac, may be any one of several ships commissioned in the United States Navy and named after the Merrimack River.
- USS Merrimack (1798), 1798–1801, later known as the Monticello, sunk off Cape Cod
- USS Merrimack (1855), 1856–1860, best known as the hull upon which ironclad CSS Virginia was built during the American Civil War
- USS Merrimac (1864), 1864–1865, a side-wheel steamer
- USS Merrimac (1898), 1898, a collier sunk during the Spanish-American War
- USS Merrimack (AO-37), 1942–1954, a Kennebec-class fleet oiler, served in both the Atlantic and Pacific during World War II
- USS Merrimack (AO-179), 1981–1998, a Cimarron-class fleet oiler
| This article includes a list of ships with the same or similar names. If an internal link for a specific ship led you here, you may wish to change the link to point directly to the intended ship article, if one exists. |