In ancient Roman religion and mythology, Tellus or Terra ("Mother Earth") is the personification of the Earth. Although Tellus and Terra are hardly distinguishable during the Imperial era, Tellus was the name of the original earth goddess in the religious practices of the Republic or earlier. The scholar Varro (1st century BC) lists Tellus as one of the di selecti, the twenty principal gods of Rome, and one of the twelve agricultural deities. She is regularly associated with Ceres in rituals pertaining to the earth and agricultural fertility.

The attributes of Tellus were the cornucopia, bunches of flowers, or fruit. She was typically depicted reclining, or rising, waist high from a hole in the ground. Her male complement was a sky god such as Caelus (Uranus) or a form of Jupiter. Her Greek counterpart is Gaia, and among the Etruscans, her name was Cel. Michael Lipka has argued that the Terra Mater who appeared during the reign of Augustus, is a direct transfer of the Greek Ge Mater into Roman religious practice, while Tellus, whose ancient temple was within Rome's sacred boundary (pomerium), represents the original earth goddess cultivated by the state priests.

The two words terra and tellus are thought to derive from the formulaic phrase tersa tellus, meaning "dry land".^{[citation needed]} The etymology of tellus is uncertain; it is perhaps related to Sanskrit talam, "plain ground".

The 4th century AD Latin commentator Servius distinguishes between use of tellus and terra. Terra, he says, is properly used of the elementum, earth as one of the four classical elements with air (Ventus), water (Aqua), and fire (Ignis). Tellus is the goddess, whose name can be substituted (ponimus ... pro) for her functional sphere the earth, just as the name Vulcanus is used for fire, Ceres for produce, and Liber for wine. Tellus thus refers to the guardian deity of Earth and by extension the globe itself. Tellus may be an aspect of the spirit called Dea Dia by the Arval priests, or at least a close collaborator with her as "divinity of the clear sky."

Varro identifies Terra Mater with Ceres:

Not without cause was the Earth (Terra) called Mater and Ceres. It was believed that those who cultivated her led a pious and useful life (piam et utilem ... vitam), and that they were the sole survivors from the line of King Saturn.

Ovid distinguishes between Tellus as the locus ("site, location") of growth, and Ceres as its causa ("cause, agent"). Mater, the Latin word for "mother," is often used as an honorific for goddesses, including Vesta, who was represented as a virgin. "Mother" therefore is an honorific that expresses the respect one would owe any good mother. Tellus and Terra are both regarded as mothers in both the literal and honorific sense; Vesta in the honorific only.

The Temple of Tellus was the most prominent landmark of the Carinae, a fashionable neighborhood on the Oppian Hill. It was near homes (domūs) belonging to Pompey and to the Cicero family.