Kazimierz III of Gniewkowo

1280/84 – 22 August 1345/13 May 1350), was a Polish prince member of the House of Piast, Duke of Inowrocław during 1287-1314 (under the regency of his mother until 1294 and his brother during 1294–1296), since 1306 vassal of the Kingdom of Poland, Governor of the Duchy of Pomerelia (Gdańsk Pomerania) during 1306-1309 (on behalf of his uncle Władysław I the Elbow-high), after 1314 ruler over Gniewkowo (between 1332 and 1343 deposed by the Teutonic Order).

1302, but initially ruled jointly with his brothers; two years previously (in 1300) he was forced to paid homage to King Wenceslaus II of Bohemia.

[1] In 1314 was made the formal division of the paternal inheritance between Kazimierz III and his brothers; as the youngest son, he received the small district of Gniewkowo.

Kazimierz III, unable to defend his Duchy and not wanting to be captured, decided to escape after burning the main fortress.

His fate after the loss of his domains is uncertain, because he only appears during the Second Polish-Teutonic Trial (4 February-15 September 1339), where he testified, and during the Treaty of Kalisz (8 July 1343), where thanks to the provisions arranged there he was able to return to his Duchy.