A solar deity or sun deity is a deity who represents the Sun or an aspect thereof. Such deities are usually associated with power and strength. Solar deities and Sun worship can be found throughout most of recorded history in various forms. The Sun is sometimes referred to by its Latin name Sol or by its Greek name Helios. The English word sun derives from Proto-Germanic *sunnǭ.

In ancient Greek religion and mythology, Helios is the god who personifies the Sun. His name is also Latinized as Helius, and he is often given the epithets Hyperion and Phaethon. Helios is often depicted in art with a radiant crown and driving a horse-drawn chariot through the sky. He was a guardian of oaths and also the god of sight. Though Helios was a relatively minor deity in Classical Greece, his worship grew more prominent in late antiquity thanks to his identification with several major solar divinities of the Roman period, particularly Apollo and Sol. The Roman Emperor Julian made Helios the central divinity of his short-lived revival of traditional Roman religious practices in the 4th century AD.