Marius may refer to:
- Marius (name), a male given name, a Roman family name, and a modern surname
- Gaius Marius, Roman general and statesman.
- Marcus Aurelius Marius, emperor of the Gallic Empire circa 269
- Marius (crater), on the Moon
- Marius Hills, on the Moon
- Marius (film), written by Marcel Pagnol
- "Marius" (Anderson), a science fiction story by Poul Anderson
- Măriuş, a village in Valea Vinului Commune, Satu Mare County, Romania
- Marius Pontmercy, a young male character in Les Misérables written by Victor Hugo