In ancient Greek religion, Hera (/ˈhɛrə, ˈhɪərə/; Ancient Greek: Ἥρα, romanized: Hḗrā; Ἥρη, Hḗrē in Ionic and Homeric Greek) is the goddess of marriage, women, and family, and the protector of women during childbirth. In Greek mythology, she is queen of the twelve Olympians and Mount Olympus, sister and wife of Zeus, and daughter of the Titans Cronus and Rhea. One of her defining characteristics in myth is her jealous and vengeful nature in dealing with any who offended her, especially Zeus's numerous adulterous lovers and illegitimate offspring.

Her iconography usually presents her as a dignified, matronly figure, upright or enthroned, crowned with a polos or diadem, sometimes veiled as a married woman. She is the patron goddess of lawful marriage. She presides over weddings, blesses and legalises marital unions, and protects women from harm during childbirth. Her sacred animals include the cow, cuckoo, and peacock. She is sometimes shown holding a pomegranate as an emblem of immortality. Her Roman counterpart is Juno.

The name Hera (Hēra or Hērē) has several possible and mutually exclusive etymologies. One possibility is to connect it with Greek ὥρα (hōra, season) or, according to Plato, with ἐρατή (eratē, "beloved"); another one is to interpret it as "ripe for marriage". as Zeus is said to have married her for love. According to Plutarch, Hera was an allegorical name and an anagram of aēr (ἀήρ, "air"). So begins the section on Hera in Walter Burkert's Greek Religion. In a note, he records other scholars' arguments "for the meaning Mistress as a feminine to Heros, Master", with uncertain origin. John Chadwick, a decipherer of Linear B, remarks "her name may be connected with hērōs (ἥρως, 'hero'), but that is no help since it too is etymologically obscure." A. J. van Windekens proposes the meaning "young cow, heifer", which is consonant with Hera's common epithet βοῶπις (boōpis, "cow-eyed"). Robert S. P. Beekes has suggested a Pre-Greek origin. Her name is attested in Mycenaean Greek, written in Linear B syllabary as 𐀁𐀨 e-ra, appearing on tablets found in Pylos and Thebes; it is attested also in the Cypriotic dialect, in the dative form e-ra-i.

The Proto-Indo-European root might have meant either 'the female who is attached/coupled' or 'the female who attaches herself' (as in both socially and physically or emotionally).

Many theophoric names, such as Heracles, Heraclitus, Herodotus and Herodicus, derive from Hera.

Hera bore several epithets in the mythological tradition and in literature. In the historical times the majority of the Greeks recognized Hera as the consort of Zeus. Hera is the protector of marriage and of the rights of the married women. In some cults she has some functions of the earth goddess. She is occasionally related to warfare as tutelary goddess.

In historical times, the majority of the Greeks recognized Hera as the consort of Zeus. Zeus was the protector of rights and mores, and his partner Hera became the protector of legal marriage and the rights of married women . Hera emerged from a form of the "Mycenean goddess of the palace" and became the spouse of Zeus. Modern scholars suggest that Hera is not only the Olympian sky-goddess, but in some cults she may be identified with the earth-goddess. Her ancient connection with her sacred animal, the cow, still existed in historical times. She is probably related to Near-Eastern forms of cow-goddesses such as Hathor or Bat. The Greek earth-goddess Gaia is occasionally identified with Hera. Gaia may be related to the Vedic earth-goddess Prithvi, who was also associated with the cow and is the consort of Dyaus.

An inscription in Linear B on a tablet found at Pylos mentions offerings "to Zeus-Hera-Drimios"; Drimios is the son of Zeus. Hera was the tutelary goddess of Argos and it is possible that she had Mycenean origin. Martin P. Nilsson suggested that Hera is mainly the "Argeiē" (Ἀργείη), a name given by Homer which describes her not as Greek, but as an Argive goddess. She is the protectress of the citadel. In literature Argos is called "dōma Hēras" (the house of Hera) and the Argives are called her people by Pindar. Homer in Iliad uses the formula "boōpis potnia Hērē)" (cow-eyed, mistress Hera), which probably relates her to a form of the Mediterranean goddess of nature. The epithet Qo-wi-ja ( boōpis) appears in a Linear B inscription. Walter Burkert notices that it is difficult to confirm that the epithet "bowpis" corresponds to a Greek belief. However it is possible that Hera was conceived as a cow in her archaic cults.