Castellans of the Polish–Lithuanian Commonwealth

Castellans of the Polish–Lithuanian Commonwealth were the lowest rank of territorial official who could sit in the Senate of Poland.

Their numbers varied over time and with the shifting borders of the Commonwealth.

In the Kingdom of Poland and later in the Polish–Lithuanian Commonwealth, Castellans (Polish: Kasztelan) usually deferred to the higher ranking Voivodes (Polish: Wojewoda), excepting three Distinguished Castellans of the cities of Trakai, Vilnius, and of Kraków - who ranked higher than the Voivodes.

Two castellans in the Grand Duchy of Lithuania - those of Vilnius and Trakai - were also considered privileged, and had a status equal to a voivode.

From 1565, the principle of "incompatibilitas" - "incompatibility" - precluded Voivodes and Castellans from holding a second ministerial role, except for the post of Hetman.