Detail from "The Procession of the Trojan Horse in Troy" by Giovanni Domenico Tiepolo

The Trojan Horse is part of the myth of the Trojan War, though it does not figure in the part of the war narrated in Homer's Iliad.

The Greek siege of Troy had lasted for ten years. The Greeks devised a new ruse - a giant hollow wooden horse. It was built by Epeius and filled with Greek warriors led by Odysseus. The rest of the Greek army appeared to leave whilst actually hiding behind Tenedos and the Trojans accepted the horse as a peace offering. A Greek spy, Sinon, convinced the Trojans the horse was a gift despite the warnings of Laocoon and Cassandra. Helen and Deiphobus even investigated the horse. The Trojans celebrated the raising of the siege hugely, and when the Greeks emerged from the horse the city was in a drunken stupor. The Greek warriors opened the city gates to allow the rest of the army access and the city was ruthlessly pillaged - all the men were killed and all the women taken into slavery.

There is a small museum founded in 1955 within the territories of ancient city Troy, near the Dardanelles (present-day Turkey). The museum includes the remnants of the city and a symbolic wooden horse built in the garden of the museum to depict the legendary Trojan horse.

Based on this mythological episode, we get the term, Trojan horse, in which a supposed talent or apparent advantage is actually a curse, or "Trojan horse" tactics which are underhand. The term can also refer to a "sneak attack" in general. We also get the Latin phrase "equo ne credite, Teucri! Quidquid id est, timeo Danaos et dona ferentes" (don't trust the horse, Trojans! Whatever it is, I fear Greeks even when they are bringing gifts) spoken by Laocoon in Virgil's Aeneid which covers the siege of Troy in book II. This has led to the modern saying "Beware of Greeks bearing gifts."

• For the computing use of the term, see Trojan horse (computing).
• The Trojan Horse is a movie about the alleged PLO strategy in the course of Arab-Israeli conflict.