Wartislaw I, Duke of Pomerania

Ratibor, Wartislaw's brother, founded Stolpe Abbey, Pomerania's oldest monastery, in Wartislaw's memory.

Wartislaw I (Warcisław I; – August 9, 1135) was the first historical ruler of the Duchy of Pomerania and the founder of the Griffin Dynasty.

Most of the information about him comes from the writings on the life of Otto of Bamberg. He was of Slavic origin, most likely born around the turn of the twelfth century. Early in life he was probably a "crypto-Christian", after being baptized while a prisoner of the Saxons, because he wanted to hide his new religion from his still pagan subjects. In 1109 Wartislaw was defeated in the Battle of Nakło by Bolesław III Wrymouth, the Duke of Poland. By 1112, Wartislaw had failed to keep faith with Bolesław, who in response besieged Nakło. This led to Wartislaw reswearing fealty to Bolesław. A year later he was again violating the terms of the agreement with Bolesław, which result in a military campaign against him. Faced with overwhelming odds, Wartislaw agreed to pay tribute to Bolesław, as well as to Christianize Pomerania. To that effect, he, along with Bolesław, backed Otto of Bamberg in his successful Conversion of Pomerania. By 1124 his residence was in (Kammin) Kamień Pomorski.

The last time he is mentioned explicitly in chronicles is by Saxo Grammaticus who describes a joint Polish-Danish expedition against Wartislaw around 1129/1130, which was directed at the islands of Wolin and Uznam. The Danish King Niels is supposed to have taken him prisoner but released later after the intervention of "King of the Obotrites" Canute Lavard.

He had two sons and a daughter: Bogusław I, Duke of Pomerania, Casimir I, Duke of Pomerania, and Woizlava, who married Pribislav of Mecklenburg.

Wartislaw was murdered sometime between 1134 and 1148, and was succeeded by his brother Ratibor I. The site of Wartislaw's death near Stolpe in the modern district of Vorpommern-Greifswald, where he is said to have been slain by pagans, is marked by a rock called Wartislawstein with an engraved Christian cross in remembrance of his missionary efforts.