Hercules and Deianira (c. 1470) by Antonio del Pollaiuolo

Hercules fought the river god Achelous for the hand of Deianeira, princess of Calydon, tearing off the god's horn in victory. While ferrying his new wife across the river Evenos, the centaur Nessus attempted to abduct her. Hercules shot him with a Hydra-poisoned arrow. With his dying breath, Nessus told Deianeira to keep his blood as a "love charm" — knowing it was lethal.