Philoctetes (Ancient Greek: Φιλοκτήτης Philoktētēs; English pronunciation: /ˌfɪləkˈtiːtiːz/, FILL-ək-TEE-teez), or Philocthetes, according to Greek mythology, was the son of Poeas, king of Meliboea in Thessaly, and Demonassa or Methone. He was a Greek hero, famed as an archer, and a participant in the Trojan War.

Philoctetes was the subject of four different plays of ancient Greece, each written by one of the three major Greek tragedians. Of the four plays, Sophocles' Philoctetes is the only one that has survived. Sophocles' Philoctetes at Troy, Aeschylus' Philoctetes and Euripides' Philoctetes have all been lost, with the exception of some fragments. Philoctetes is also mentioned in Homer's Iliad, Book 2, which describes his exile on the island of Lemnos, his being wounded by snake-bite, and his eventual recall by the Greeks. The recall of Philoctetes is told in the lost epic Little Iliad, where his retrieval was accomplished by Diomedes. Philoctetes killed three men at Troy.

Philoctetes was described by the chronicler Malalas in his account of the Chronography as "a good height, well set, dark skinned, eyebrows meeting, brave, good eyes, good nose, black hair, hairy, sensible, accurate archer, magnanimous".

Philoctetes was the son of Poeas, king of Meliboea in Thessaly. He came into possession of the bow and arrows of Heracles after assisting the hero in ending the agony of the shirt of Nessus—Philoctetes, or in some versions his father, lit the pyre on which Heracles immolated himself and became immortal. Philoctetes then received the favor of the newly deified Heracles.

Philoctetes had been one of the many eligible Greeks who competed for the hand of Helen, the Spartan princess; as such, he was required to participate in the expedition to reclaim her for Menelaus that became the Trojan War. However, on the way to Troy, Philoctetes was left behind and stranded on the island of Lemnos. There are at least four stories about what caused the Greeks to abandon Philoctetes, but in every version he received a wound on his foot that festered and had a terrible smell.

One version holds that Philoctetes was bitten by a snake that Hera sent to molest him as punishment for the service rendered to Heracles, since Hera was portrayed in one tradition as the adversary of Heracles. The snakebite recurs in a version that has the Achaeans, en route to Troy, coming to the island of Tenedos, where Achilles angered Apollo by killing King Tenes, allegedly the god's son. When the Achaeans were sacrificing to Apollo in expiation, a snake came out from the altar and bit Philoctetes.

Another tradition says that the Greeks forced Philoctetes to show them where Heracles's ashes were deposited. Philoctetes would not break his oath by speech, but he went to the spot and placed his foot upon the site. The foot that touched the soil over the ashes immediately suffered a wound.

In a fourth version, Philoctetes received his terrible wound on the island of Chryse when he unknowingly trespassed the shrine of the nymph after whom the island was named. (This is the version in the extant play by Sophocles.) A modern interpretation is that he was scratched by a poisoned arrow. Commonly tips of arrows were poisoned with a combination of fermented viper venom, blood or plasma, and feces. A person who survived would have a festering wound, though even a scratch could result in death, sometimes drawn out.