Nessus, the river's ferryman and killer of Heracles
Nessos, the son of Ixion and Nephele, was a Centaur who acted like a ferryman in the River Evinos, passing pedestrians across the river on his back. He used to have a bad relationship with the Greek hero Heracles.
One day, Heracles got to the river with Deianira, his third wife. Heracles was strong and could pass the river all by himself, but he confided his wife to Nessus to ferry her across. Nessus however attempted to kidnap(or rape) Deianeira, and Hercules killed the centaur him with arrows dipped in poison.
Before he died, Nessos managed to give Deianeira a love potion mixed with his blood and semen, telling her to soak a robe of Hercules in it so that he would never be unfaithful to her again. This filter burned the great Greek mythical hero, Heracles, fatally with terrible pain.