Justifier may refer to:
- Something which justifies
- In the theory of justification, something which justifies a belief
- Konami Justifier, a light gun used in video arcade and home console games
- One of the Justifiers, fictional soldiers in the DC Comics universe
- "Justifier", a song by Australian pop/rock band Big Pig
- Justifier, fictional flying ship in the Marvel Comics universe, used by vigilante team The Jury
- Justifier, an alternate Dungeons & Dragons character class