In Egyptian mythology, Tefnut (alternate spellings Tefenet, Tefnet) is a goddess of water and fertility, indeed her name means moist waters (i.e. rain). She was created by Atum (a solar god, as were Ra, Horakty, and Khepri) from his mucus, a mythology that may be related to the alternative translation of her name - spat waters. Another version (the Memphite version of the myth) states that Atum sneezed once and Tefnut's brother Shu was born, and when he coughed to clear his throat Tefnut was born. With her brother, Shu, she was the mother of Geb and Nut. In a third version, Atum masturbated and his semen formed Tefnut, and his breath, her brother Shu.

In a myth describing the terrible weather disaster at the end of the Old Kingdom it was said that Tefnut (moisture) and Shu once argued, and she left Egypt. The myth states that Shu quickly decided he missed her, but she fled to Nubia (somewhere much more temperate), and changed into a cat (symbolic of war), destroying any man or god that approached. Thoth, disguised, eventually succeeds in convincing her to return. Tefnut is sometimes depicted as lioness in reflection of this tale. She is also shown as a lioness headed goddess. In pictures Tefnut is usually seen lying between the firmament and the earth.

Tefnut was buried in a pyramid.