Reiner may refer to:
- Carl Reiner, American film director, screenwriter, actor and father of Rob Reiner
- Fritz Reiner, early-20th-century American conductor
- Irving Reiner, American mathematician
- Jared Reiner, American professional basketball player
- Markus Reiner, engineer and scientist, one of the founders of rheology
- Rob Reiner, American film director, screenwriter, actor and son of Carl Reiner
- Vincentio Reiner (Renieri, Reinieri), a 17th-century Italian astronomer and mathematician
- Reiner Erlings, a Dutch composer and music producer
- Reiner Knizia, a board game designer
- Reiner (crater), a crater on the Moon, named after Vincentio Reiner