Peirce Crosby (16 January 1824 - 15 June 1899) was an admiral in the United States Navy, who served during the Civil War.

Born in Delaware County, Pennsylvania, Crosby was appointed midshipman in June 1838. He reached the rank of Lieutenant in September 1853 after a decade and a half in ships of the Home and Mediterranean Squadrons, plus coast survey duty. He served in Decatur and Petrel in the Mexican-American War, and had shore assignments in and around Philadelphia, Pennsylvania. From late 1853 until the outbreak of the Civil War in the spring of 1861, Lieutenant Crosby served in the sloops of war Germantown, of the Brazil Squadron , and Saratoga, and on board the receiving ship Princeton at Philadelphia.

During April-October 1861, as the War between the States ran through its first half year, Crosby served in the sloop of war Cumberland and briefly commanded the new gunboat Pembina . He went to the Gulf of Mexico as Commanding Officer of the gunboat Pinola at the beginning of 1862. In Pinola, assisted by Itaska, he broke the chain barrier across the Mississippi to make possible the passage upriver of Flag Officer David Farragut's squadron, and the capture of New Orleans. For two years beginning in November 1862, Crosby helped enforce the blockade of the Confederacy's East Coast as Commanding Officer of the steamers Sangamon , Florida, and Keystone State, and as Fleet Captain of the North Atlantic Blockading Squadron. He finished the war in the Gulf, commanding the gunboat Metacomet, and took part in clearing mines from Mobile Bay.

Commander Crosby spent the first three years of the post-Civil War era in the south Atlantic as Commanding Officer of the gunboat Shamokin . Following promotion to Captain in May 1868, he had a variety of shore assignments and, in 1872-1873, commanded the big steamer Powhatan. In 1877-1881, in the rank of Commodore, Crosby was commandant of the League Island (Philadelphia) Navy Yard. He finished his active career as a Rear Admiral, commanding the South Atlantic Station in 1882-1883 and the Asiatic Station later in 1883. In October of the latter year he was placed on the Retired List.

Rear Admiral Peirce Crosby died at Washington, D.C., on 15 June 1899 and is buried in Arlington National Cemetery.

USS Crosby (DD-164 was named for him.