Androgyny is the possession of both masculine and feminine characteristics. Androgyny may be expressed with regard to gender expression.

When androgyny refers to mixed biological sex characteristics in humans, it often refers to conditions in which characteristics of both sexes are expressed in a single individual. These are known as intersex people, or those who are born with congenital variations that complicate assigning their sex at birth, as they do not correspond entirely to the male or female sexes.

The term derives from Ancient Greek: ἀνδρόγυνος, from ἀνήρ, stem ἀνδρ- (anér, andro-, meaning man) and γυνή (gunē, gyné, meaning woman) through the Latin: androgynus.

Androgyny is attested from earliest history and across world cultures. In ancient Sumer, androgynous men were heavily involved in the cult of Inanna. A set of priests known as gala worked in Inanna's temples, where they performed elegies and lamentations. Gala took female names, spoke in the eme-sal dialect, which was traditionally reserved for women, and appear to have engaged in sexual acts with men.

In later Mesopotamian cultures, kurgarrū and assinnu were servants of the goddess Ishtar, Inanna's East Semitic equivalent, who dressed in female clothing and performed war dances in Ishtar's temples. Several Akkadian proverbs seem to suggest that they may have also engaged in sexual activity with men. Gwendolyn Leick, an anthropologist known for her writings on Mesopotamia, has compared these individuals to the contemporary Indian hijra. In one Akkadian hymn, Ishtar is described as transforming men into women.

The ancient Greek myth of Hermaphroditus and Salmacis, two divinities who fused into a single immortal, provided a frame of reference used in Western culture for centuries. Androgyny and homosexuality are also seen in Plato's Symposium, in a myth where, according to Aristophanes, humanity started as three sexes: male-male people that descended from the sun, female-female people who descended from Earth, and male-female people who came from the Moon. The androgynous humans were spherical and had four legs, four hands and two heads. They were also extremely powerful and dared rebel against the Greek pantheon. "Plato cites the ancient tale of Otus and Ephialtes who rebelled against the gods and drove them from Mount Olympus. Not satisfied with this, they tried to set Mount Ossa atop Mount Olympus, and Mount Pelion atop of Ossa, that they might attack the gods in heaven itself."

The gods, angered, divided the primordial humans in two and scattered them across the Earth. The divided searched for their other halves. The women who sought another woman and the men who sought another men were homosexuals.

The Mishnah, a foundational text of Rabbinic Judaism from 2nd century Syria Palaestina, uses the term androgynos 32 times. It also recounts the creation of humanity in the Genesis creation narrative in Platonic terms. Genesis Rabbah, a midrashic text written some time after the Mishnah, explains, "Adam, who was created alone and thus embodies all of mankind, was androgynous, i.e. a bi-sexual being, male and female bound together in a single male-female body: 'He created him androgynous . . . He created him double-faced.'" It is one of four additional legal categories of transgressively sexed individuals in the text, alongside the ayelonit, tumtum, and saris. In one mention, Rabbi Meir describes the androgynos as "a creation of its own type, which the sages could not decide whether is male or female".