Catherine of Masovia (Polish: Katarzyna mazowiecka; 1413/16[1] – between 2 June 1479 and 5 July 1480[2]) was a Polish princess member of the House of Piast in the Masovian branch.
She was the eighth and youngest daughter of Siemowit IV, Duke of Masovia and Alexandra, a daughter of Algirdas, Grand Duke of Lithuania and sister of King Władysław II Jagiełło of Poland.