Atalanta (/ˌætəˈlæntə/; Ancient Greek: Ἀταλάντη, romanized: Atalántē, lit. 'equal in weight') is a heroine in Greek mythology.

There are two versions of the huntress Atalanta: one from Arcadia, whose parents were Iasus and Clymene and who is primarily known from the tales of the Calydonian boar hunt and the Argonauts; and the other from Boeotia, who is the daughter of King Schoeneus and is primarily noted for her skill in the footrace. In both versions, Atalanta was a local figure allied to the goddess Artemis; in such oral traditions, minor characters were often assigned different names, resulting in minor regional variations.

At birth, Atalanta was taken to Mount Parthenion to be exposed because her father had desired a son. A she-bear—one of the symbols of Artemis—whose cubs had been recently killed by hunters came upon Atalanta and nursed her until those same hunters discovered her and raised her themselves in the mountains. Atalanta then grew up to be a swift-footed virgin who eschewed men and devoted herself to the huntress Artemis.

Atalanta modelled herself after Artemis, wearing a simple sleeveless tunic that reached her knees and living in the wilderness. While living in the wild, Atalanta slew two centaurs with her bow and arrows, Rhoecus and Hylaios, after her beauty caught their attention and they attempted to rape her.

Atalanta is only occasionally mentioned in the legend of the Argonauts; however, her participation is noted in Pseudo-Apollodorus's account, which says that during the search for the Golden Fleece, Atalanta, who was invited and invoked the protection of Artemis, sailed with the Argonauts as the only woman among them. In Diodorus Siculus's account, Atalanta is not only noted to have sailed with the Argonauts but to have fought alongside them at the battle in Colchis, where she, Jason, Laertes, and the sons of Thesipae were wounded and later healed by Medea. In the account of Apollonius of Rhodes, Jason prevents Atalanta from joining not because she lacks skill but because as a woman she has the potential to cause strife among men on the ship.

After the death of King Pelias in Iolcus, funeral games were held in which Atalanta defeated Peleus in a wrestling match. This match became a popular subject in Greek art.

In an annual celebration, King Oeneus of Calydon had forgotten to honour Artemis with a sacrifice in his rites to the gods. In anger, she sent the Calydonian boar, a monstrous wild boar that ravaged the land, cattle, and people, and prevented the crops from being sown. Atalanta was called upon to join Meleager, Theseus, Pollux, Telamon, Peleus, and all those who were part of the Argonaut expedition on the hunt for the boar. Many of the men were angry that a woman was joining them, but Meleager, though having a family of his own, convinced them otherwise as he desired to father a child with Atalanta after hearing of her expertise in archery and beauty while hunting.

During the hunt Hyleus and Ancaeus were killed, Peleus accidentally killed a fellow hunter and others were wounded. Atalanta drew first blood on the boar with her bow. After this feat, killing the boar became a collective effort as, after the initial blow, Amphiaraus shot the boar's eye and Meleager ended its life. Meleager awarded the hide to Atalanta for her valor, but it was taken away by Meleager's uncles, Plexippus and Toxeus, who considered it dishonorable for a woman to hold such a prize. In response, Meleager killed his uncles. Althaea, Meleager's mother, became grief-stricken after hearing of her brothers’ deaths and threw the log that was tied to her son's life into a fire, killing him.