Swietopelk II, also Zwantepolc II or Swantopolk II, (1190/1200 — 11 January 1266), sometimes known as the Great (Świętopełk II Wielki; Swiãtopôłk II Wiôldżi), was the ruling Duke of Pomerelia-Gdańsk from 1215 until his death. He was the first member of the Samborides to style himself dux from 1227 onwards.
The duke is known under many spellings (Swantepolk, Swantipolk, Svatopluk, Swietopelk, Swatopolk, Sviatopolk, Światopełek, Świętopełk, Swiãtopôłk), of which Domin(us) Zwantepolc(us) D(ux) Danceke and Svantopelc Ducis Pomeranie were used on seals.
Swietopelk was the son of the Pomeranian duke Mestwin I and his wife Swinisława. His father had ruled over Eastern Pomerania (or Pomerelia) since about 1205 by appointment of the Polish high duke Władysław III Spindleshanks. In 1216 or 1217 his son Swietopelk was made a steward over Pomerelia by High Duke Leszek I the White of Kraków. He was responsible for the Gdańsk territory, the largest of the four portions of Pomerelia. In 1218, Swietopelk took advantage of a revolt of local knights against Danish rule to occupy the Lands of Schlawe and Stolp. After his brother Warcislaw died without heirs, Swietopelk took over his Lubiszewo Tczewskie.
Upon their father's death, Swietopelk's brothers Sambor and Racibor were still young, so he acted as their guardian. As they came of age, the brothers received their share of inheritance: Sambor received Lubiszewo Tczewskie and Racibor received Białogard.
Swietopelk, who had exploited Piast Poland's fragmentation to gain independence, promised Władysław Odonic the throne of Kraków and Silesia in exchange for his support in the ousting of Leszek and Henry I the Bearded of Lower Silesia . On 23 November 1227, on the occasion of an assembly of Piast dukes in Gąsawa, Leszek was killed in an ambush set by Swietopelk II and perhaps Władysław, while Henry was severely wounded.
In 1233-34, Swietopelk II, with his brother Sambor, joined a crusading army along with Hermann Balk, Konrad I of Masovia, Henry the Bearded, and Władysław Odonic.