Hercules was one of the principal heroes of Greek mythology. The Greeks called him Herakles, but I will use the Roman name Hercules which is more familiar to most people.
We have already looked at the twelve labors of Hercules. Today we look at two other myths. The fresco above shows Hercules at left, carrying his trademark lion skin and club, with the river god Achelous and Deianeira, daughter of the king of Calydon.
This fresco is in a house in the Roman town of Herculaneum. The town was named after Hercules and was destroyed by the same eruption of Mount Vesuvius that destroyed Pompeii in 79 A.D.

Both Hercules and Achelous wanted to marry Deianeira, and they fought over her. Achelous, being a god, was able to change shape. He transformed himself into a snake. Above, Hercules fighting Achelous in the form of a snake, by Francois-Joseph Bosio, 1824, in the Louvre museum.
The front view of Hercules fighting Achelous as a snake. Amusingly, it looks like Hercules is holding a can of beer or soda, but I guess it's supposed to be a rock.
Unable to win as a snake, Achelous then transformed himself into a bull. Above, Hercules fighting Achelous in the form of a bull, a 17th century sculpture by Ferdinand Tacca. Ultimately, Hercules won the fight, and he married Deianeira.
A second myth involves the centaur Nessus. A centaur was half horse, half man. Above, a fresco in Pompeii showing Hercules, Deianeira and Nessus. Nessus acted as a ferryman, carrying passengers across the river Euenos. In this story, Nessus carried Deianeira across the river, then tried to rape her while Hercules was still on the other side of the river. Hercules could see what was happening, and he shot Nessus with an arrow that was poisoned with the blood of the Hydra, a monster that Hercules had killed in his earlier twelve labors.
This vase from 420 BC shows Hercules attacking Nessus, but it omits the poisoned arrow, which is vital to the myth, as we will see.
Here's a 2nd century Roman sculpture of Hercules attacking Nessus, again omitting the poisoned arrow.
And here's the rear view of that same sculpture in the Uffizi gallery in Florence, Italy.
The myth continues. As Nessus lay dying, he gave Deianeira his blood-soaked robe, telling her that if she gave it to Hercules, it would ensure that Hercules would be true to her forever. Actually, he knew that his blood was deadly, infected with the virulent poison of the Hydra.
Later, Deianeira told Hercules' servant Lichas to give Hercules the robe. When Hercules put on the robe, the poison blood in the robe burned his skin. Thinking that Lichas was behind this, Hercules threw Lichas into the sea.
Above, Hercules and Lichas by the sculptor Antonio Canova, 1815. Canova concealed Hercules' genitals with a fig leaf ...
but interestingly, if you look from below, Canova's sculpture shows Hercules' balls behind the fig leaf (above).
Here's a modern painting of Hercules and Lichas by William Horace Littlefield, 1937.
Even without the robe, the poison continued to burn Hercules, and it became unbearable. So Hercules lit a funeral pyre and jumped onto it, burning to death, as seen in this 1655 illustration by Michel de Marolles. A dramatic end for a dramatic mythical hero.