Was the Trojan Horse ( Ancient Greek mythology) real or a myth?
There is no solid historical evidence that the Trojan War, with all the stories arising from it as told in the Iliad, the Odyssey (and to a lesser extent the Aeneid), ever actually took place and is anything more than just a story. It is possible that it did though. As for the details such as the Trojan Horse, the semi-mortal Achilles being killed by an arrow in his heel, Odysseus wandering the oceans for 10 years trying to get home afterwards and meeting with witches… one would suspect these are all embellishments. In fact to me, their presence at every turn of the narrative suggests that the entire conflict is a dramatic invention and not based on historical fact, but prior to Homer there was something of a Dark Age in terms of written texts, so it is possible that his epic poem was based on an actual historic siege-battle that took place and merely embellished to make a better story rather than fabricated from scratch.
