Gaius Marius (157 BCE – January 13, 86 BCE) is a Roman general and statesman.

He is elected consul an unprecedented seven times during his career.

He is also noted for his dramatic reforms of Roman armies, authorizing recruitment of landless citizens, eliminating the manipular military formations, and reorganizing the structure of the legions into separate cohorts.

Marius defeats the invading Germanic tribes (the Teutones, Ambrones, and the Cimbri), for which he is called "the third founder of Rome."

His life and career are significant in Rome's transformation from Republic to Empire.