Orion (Ωριων) was the only lover of Artemis.
Orion was born to the god Poseidon who gave him the ability to walk on water.
One day while he was visiting Chios, he saw and fell in love with the princess, Merope. Her father told him he may marry her if he could clear the island of wild beasts. Orion did so, and asked again for her hand in marriage. Her father still told him no, and he tried to kidnap her in a flurry of anger. His eyes were poked in the process, rendering him blind. He was exiled from Chios, and treated like a criminal.
He wandered into the forge where Hephaestus worked, and pleaded for help. Hephaestus told Cedalion to escort him to palace of Helios. Cedalion did so, and Helios restored his sight. Orion then went back to Chios, wishing to kill the king. He offered his daughter to Orion, but Orion didn't care for her any more. Before he could kill him, he became distracted, and the king hid underground.
Orion and Artemis became hunting partners, and hunted many animals and monsters together. They soon became in love, which would break Artemis's vow to be a virgin forever.
Apollo, either jealous of his sister's infatuation or wishing to keep her vow, sent a scorpion, Scorpio, to kill him. The scorpion stabbed him in the heel, killing him. In grief, Artemis put Orion in the stars.
In another myth, Apollo instead issued a challenge to Artemis. He said she couldn't hit the target out in the sea, which was actually Orion, and she took the challenge. She hit him with perfect accuracy, and became distraught because of the murder. Apollo then hung him in the stars.
In another myth, Gaea sent Scorpio after Orion because he was killing off all the animals of the world.