USS Greer (DD–145) was a Wickes-class destroyer in the United States Navy, the first ship named for Rear Admiral James A. Greer (1833–1904). In what became known as the "Greer incident," she became the first US Navy ship to fire on a German ship, three months before the United States officially entered World War II. The incident led President Franklin D. Roosevelt to issue what became known as his "shoot-on-sight" order, with the intention of creating a casus belli in the Atlantic, provoking Germany to declare war on the US.
Greer was launched by William Cramp & Sons Ship & Engine Building Co., Philadelphia, 1 August 1918; sponsored by Miss Evelina Porter Gleaves, daughter of Rear Admiral Albert Gleaves; and commissioned 31 December 1918.