Nikolaus Storzenbecher, or Klaus Störtebeker (c. 1360 in Wismar – 20 October 1401 {1400} in Hamburg), was a leader and the best known representative of a companionship of privateers known as the Victual Brothers (German: Vitalienbrüder). The Victual Brothers (Latin "victualia") were originally hired during a war between Denmark and Sweden to fight the Danish and supply the besieged Swedish capital with provisions. After the end of the war, the Victual Brothers continued to capture merchant vessels for their own account and named themselves "Likedeelers" (literally: equal sharers).
A large number of myths and legends surround the few facts known about Klaus Störtebeker's life. Störtebeker is both a nickname and a surname (in 2015 ca. 200 persons in Northern Germany with the surname Störtebeker), meaning "empty the mug with one gulp" in Low Saxon. The moniker refers to the pirate's supposed ability to empty a four-litre (1.06 US gal) mug of beer in one gulp. At this time, pirates and other fugitives from the law often adopted a colorful nom de guerre.
Born in the Baltic port of Wismar, Störtebeker entered public consciousness around 1398, after the expulsion of the Victual Brothers from the Baltic island of Gotland, where they had set up a stronghold and headquarters in the town of Visby. During the following years, Störtebeker and some of his fellow captains (the most famous of whom were Gödeke Michels, Hennig Wichmann and Magister Wigbold) captured Hanseatic ships, irrespective of their origin.
Störtebeker had a stronghold in Marienhafe, East Frisia, dating from about 1396. He married a daughter of the East Frisian chieftain, Keno ten Broke (ca 1310-1376). There still exists a tower bearing his name (Störtebekerturm) at the Evangelical Lutheran Marienkirche in Marienhafe.