| Mściwoj | |
| Gender: | male |
| Meaning: | mści ("vengeance") + woj ("war, warrior") |
| Origin: | Slavic |
| Nickname: | Mszczuj |
| Related Names: | Mścisław |
Mściwój or Mściwoj is a very old 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.