SS Syren (also spelled Siren) was a privately owned iron-hulled sidewheel steamship and blockade runner built at Greenwich, Kent, England in 1863, designed for outrunning and evading the Union ships on blockade patrol around the Confederate States coastline during the American Civil War. Owned by the Charleston Importing and Exporting Company, Syren made her first run on 5 November 1863, importing supplies for the Confederacy from Nassau to Wilmington. Syren completed a record 33 runs through the Union blockade, the most of any blockade runner, before being captured while berthed at Charleston Harbor by invading Union forces.