Tiv is an Etruscan Deity of the moon. Some authorities call Him male, while others call Her female, which isn't that unusual for Etruscan Deities, as quite often the same names are used of both Gods and Goddesses. As far as I could find there were no depictions of Tiv, but Her/His name is engraved on the back of the Piacenza divination liver, a model of a sheep's liver made in bronze, representing the cosmos, which is divided off into different houses dedicated to different Gods. Tiv is one of only two names on the underside of the liver; the other being Usil, the Etruscan sun Deity; the presence of Their names on the back is usually taken to mean that the map of the sky could be divided into two main parts.

The name Tiv means "the Bright One", and is also used for both "moon" and "month"; related words in Etruscan are tiusta, "brilliant or shining" and tiurunias, an Etruscan month name, perhaps a winter month such as December, when the moon is at its highest in the sky. Tiurunia is a name for Diana or Lucina, both moon and light Goddesses, and perhaps Tiv was a similar Goddess.

Also spelled: Tiu, Tivr, Tiur