The Diocese of Samland (Sambia) (German: Bistum Samland, Polish: Diecezja sambijska) was a Latin Catholic diocese of the Catholic Church in Samland (Sambia) in medieval Prussia. It was founded in 1243 by papal legate William of Modena. Its seat was Königsberg, until 1523 the episcopal residence was in Fischhausen. The bishopric became Lutheran in the 16th century during the Protestant Reformation and was eventually dissolved following the establishment of Ducal Prussia, a Protestant vassal duchy of the Kingdom of Poland.