Marius is a male name, a Roman family name, and a modern surname.

It is thought to be derived from either[citation needed] the Roman war god Mars or from the Latin root mas or maris meaning "male".

It may also derive from the Latin word mare meaning "sea", the plural of which is maria.

In Christian times, it was syncretized as a masculine form of the unrelated feminine given name Maria, from the Hebrew Miriam, Aramaic variant Mariam, and used alongside it.

The name is also used in the Philippines, France, Denmark, Germany, the Netherlands, and South Africa.