Valeria Maximilla (fl. 293–312) was the Empress of Rome and wife of Emperor Maxentius.
She was the daughter of Emperor Galerius and his first wife, whose name is unknown. She married Maxentius around 293 (the exact date is unknown) in what was likely an attempt to forge an alliance between the families of Galerius and Maxentius' father Maximian, himself Emperor in the West. She bore two sons: the eldest, Valerius Romulus, was born c. 294; the other son's name is not recorded, but might be Aurelius Valerius, who was executed in 312. As an emperor's daughter, she was entitled nobilissima femina.
Her husband was acclaimed emperor in October 306 against the wishes of Valeria Maximilla's father, who tried to overthrow the usurper in 307 but without success. Maxentius remained the ruler of Rome, Italy and Africa until 312. Valeria's son Romulus died in 309. In 312 Constantine I invaded Italy. Valeria and her husband were together before the Battle of the Milvian Bridge, when she disappears from the historical record. Her fate is unknown.
Valeria Maximilla's portrait does not appear on any of the coinage issued under Maxentius, but she may have been depicted on a defaced sculpture now housed in the Museo Capitolino. If it is of Maximilla, it was likely defaced after her husband's overthrow, when his images were themselves defaced.
Maximilla may be the nameless queen who appears in the hagiography of St. Catherine of Alexandria by Jacobus de Voragine. In this story, the queen converted to Christianity after meeting with Catherine, and the both of them were then tortured and executed by Maxentius, depicted here as a persecutor of Christians.