Mściwój or Mściwoj is a Polish given name of Slavic origin, consists of two elements: mści "vengeance" and woj, derived from: wojna (war), wojownik (warrior) or wuj (uncle). A related name is: Mścisław. The Pomeranian form is Mestwin.
List of people with the given name Mściwój Mestwin (Mściwoj) I, Duke of Pomerania Mestwin (Mściwoj) II, Duke of Pomerania Mszczuj of Skrzynno, Polish knight