Ratnik (Russian: Ратник, lit. 'warrior') can refer to:
- Ratniks, a Bulgarian nationalist organization
- Ratnik (program), a Russian infantry combat system
- Kamerton-N Ratnik, a Russian autogyro
- Ratnik (film), a Nigerian science fiction film
- Diane Ratnik (born 19620, Canadian retired volleyball player
- Marcel Ratnik (born 2003), Slovenian footballer