Philoctetes
The title character is a Greek warrior whose real significance is that he is the owner of the magical bow of Herakles. Due to complications resulting from a snakebite (mainly his peals of pain and the stench of the infection) he was unceremoniously abandoned on the island of Lemnos by his shipmates (on orders from Odysseus) while on their way to Troy. After a decade of war, a prophet warns that the Greeks can never hope to sack Troy as long as they do not possess the magical bow of Herakles. And so Odysseus is set to learn a little lesson about karma, Greek-style.
Odysseus
The legendary hero of The Odyssey is here presented as something less than valiant. Not only was Odysseus the instigator behind marooning Philoctetes in the first place, but he heads back determined to get the bow of Herakles not through honest exchange and negotiation, but by devising a crafty trick to lure it out of the possession of its rightful owner. The hero of the Trojan War plans to truck not in karma, but eternal recurrence: once he gets the bow, he will abandon Philoctetes all over again.
Neoptolemus
The son of Achilles accompanies the older Odysseus to help retrieve the bow of Herakles. Although resistant at first, he ultimately gives in to the coercion of the older man to follow through with his plan to trick Philoctetes out of the bow rather rescuing him, but once the scheme proves successful, Neoptolemus is overcome with guilt at the sight and sound of the man who is now made completely helpless by the loss the magic.
Herakles
Herakles himself makes a cameo appearance at the end in a rare instance of Sophocles resorting to the deus ex machina to wrap everything up nice and tidy. He is lowered from the heavens in a basket with the command for Philoctetes to set sail for Troy and be rewarded by having his wound healed.
