Eros (UK: /ˈɪərɒs, ˈɛrɒs/, US: /ˈɛrɒs, ˈɛroʊs/ ^ⓘ; Ancient Greek: Ἔρως, lit. 'Love, Desire') is the Greek god of love and sex. The Romans referred to him as Cupid or Amor. In the earliest account, he is a primordial god, while in later accounts he is the child of Aphrodite.

He is usually presented as a handsome young man, though in some appearances he is a juvenile boy full of mischief, ever in the company of his mother. In both cases, he is winged and carries his signature bow and arrows, which he uses to make both mortals and immortal gods fall in love, often under the guidance of Aphrodite. His role in myths is mostly complementary, and he often appears in the presence of Aphrodite and the other love gods and often acts as a catalyst for people to fall in love, but has little unique mythology of his own; the most major exception being the myth of Eros and Psyche, the story of how he met and fell in love with his wife.

Eros and Cupid, are also known, in art tradition, as a Putto (pl. Putti). The Putto's iconography seemed to have, later, influenced the figure known as a Cherub (pl. Cherubim). The Putti and the Cherubim can be found throughout the Middle Ages and the Renaissance in Christian art. This latter iteration of Eros/Cupid became a major icon and symbol of Valentine's Day.

The Greek ἔρως, éros meaning 'desire' (whence eroticism) comes from the verb ἔραμαι, éramai and in infinitive form ἐρᾶσθαι, erãsthai 'to desire, love', itself of uncertain etymology. R. S. P. Beekes speculates a Pre-Greek origin.

Eros appears in ancient Greek sources under several different guises. In the earliest sources (the cosmogonies, the earliest philosophers, and texts referring to the mystery religions), he is one of the primordial gods involved in the coming into being of the cosmos. In later sources, however, Eros is represented as the son of Aphrodite, whose mischievous interventions in the affairs of gods and mortals cause bonds of love to form, often illicitly. Ultimately, in the later satirical poets, he is represented as a blindfolded child, the precursor to the chubby Renaissance Cupid, whereas in early Greek poetry and art, Eros was depicted as a young adult male who embodies sexual power, and a profound artist.

A cult of Eros existed in pre-classical Greece, but it was much less important than that of Aphrodite. However, in late antiquity, Eros was worshiped by a fertility cult in Thespiae. In Athens, he shared a very popular cult with Aphrodite, and the fourth day of every month was sacred to him (also shared by Herakles, Hermes and Aphrodite).

The Thespians celebrated the Erotidia (Ancient Greek: Ἐρωτίδεια) meaning festivals of Eros.

He had the epithet Klêidouchos (Κλειδοῦχος), meaning holding/bearing the keys, because he was holding the key to hearts. In addition, he had the epithet Pandemos (Πάνδημος, "common to all the people").