USS Willamette was a proposed United States Navy screw sloop-of-war or steam frigate that was cancelled in 1866 without ever having been laid down. Willamette was a wooden-hulled bark-rigged (or ship-rigged) Contoocook-class screw sloop-of-war or steam frigate with a single funnel slated to be built for the Union Navy late in the American Civil War. The contract for her construction was cancelled in 1866 before her keel was laid.