Other uses: Trojan horse (malicious computer program)
The Trojan Horse is part of the myth of the Trojan War.

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 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. The Trojans celebrated 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 is actually a curse, or 'Trojan horse' tactics which are underhand. We also get the Latin phrase "timeo Danaos et dona ferentes" (literally, I fear the Greeks even when they are bringing gifts or figuratively, Beware of Greeks bearing gifts) spoken by Laocoon in Virgil's Aeneid which tells the story of the Trojans during and after the Trojan Horse affair.