Which Roman god was the personification of the morning star?

Lucifer was the Roman personification of the morning star, the planet Venus when it appears before sunrise.

The Latin name Lucifer means “light-bringer,” combining lux, “light,” with ferre, “to carry.” Roman writers used it as the name for Venus in its morning appearance, while the same planet seen after sunset was called Vesper. Poets sometimes treated Lucifer as a male figure who carried a torch or heralded the dawn, giving the astronomical term a mythological personality.

Lucifer was not usually a major independent deity in classical Roman religion, and his myths were limited. Still, the personified morning star is conventionally identified by that name, making it the expected answer to this trivia question. A famous later confusion comes from Christian tradition, where Lucifer became associated with Satan through interpretations of Isaiah’s “morning star” imagery. That later meaning is distinct from the classical Roman figure and the planet Venus.