Telephus was the son of Heracles and Auge in Greek mythology, father of Eurypylus. His grandfather on the side of his mother, Aleus, was the king of the region of Tegea, and he had received a prophecy that he would be overthrown by his grandson. So, Aleus forced his daughter into becoming a priestess of Athena, which meant she would remain a virgin. However, when Heracles visited the area, he raped Auge and she became pregnant with Telephus. When the baby was born, Auge hid him in the temple so that her father would not find out, but the baby's cries alerted Aleus. He found Telephus and left him to die on Mount Parthenion. There, he was rescued by a deer that was sent by Heracles, and the deer provided the baby with milk and warmth. Eventually, the baby was found and adopted either by King Corycus or King Creon. Auge was then sold off as a slave, and was given as a gift to King Teuthras, who adopted her.
When Telephus reached adulthood, he left with his friend Parthenopaeus to search for a new land to settle and rule. They reached Mysia, where they helped Teuthras in a war. After the war ended, Teuthras offered the hand of Auge to Telephus. Auge was not happy with this decision and decided to kill Telephus, unaware who he really was. He tried to stab him with a knife while he was asleep, but Heracles sent a lightning bolt to separate them; on that moment, the two of them realised that they were in fact mother and son.
Telephus eventually became the successor of Teuthras to the throne of Mysia. When Paris kidnapped (or eloped with) Helen, they found themselves in Mysia, where they were welcomed by Telephus. Paris asked the king to fight off the Achaeans, should they find themselves in the area, and then left with Helen for Troy. Indeed, the Achaeans reached Mysia and a battle ensued, during which Achilles wounded Telephus who had previously killed the king of Thebes, Thersander. The wound would not heal, and after consulting the oracle of Delphi, Telephus learned that "he that wounded shall heal". So, he asked Achilles to help him, and he would help the Greeks find the way to Troy. With the help of Odysseus, Achilles scraped pieces of his spear onto Telephus' wound, which miraculously healed, thus causing the battle to end. The Greeks asked Telephus to join them in the war against the Trojans, but he refused, saying that he was the son-in-law of Priam, king of Troy. He showed them the way to Troy and the Greek army departed.