The Baralong incidents were two incidents during the First World War in August and September 1915, involving the Royal Navy Q-ship HMS Baralong and two German U-boats. Baralong sank U-27, which had been preparing to attack a nearby merchant ship, the Nicosian. About a dozen of the crewmen managed to escape from the sinking submarine and Lieutenant Godfrey Herbert, commanding officer of Baralong, ordered the survivors to be executed after they boarded the Nicosian. All the survivors of U-27's sinking, including several who had reached the Nicosian, were shot by Baralong's crew.

Q-ships, also known as Q-boats, decoy vessels, special service ships, or mystery ships, were heavily armed merchant ships with concealed weaponry, designed to lure submarines into making surface attacks. This gave Q-ships the chance to open fire and sink them.