Sisyphus was the mythical founder and first king of Corinth. He was a cunning trickster, known for his abilities to decieve gods and humans alike. He was also known as a murderer in his own kingdom, as he would often entertain himself by killing travellers to his city.
Sisyphus also reported that Zeus had abducted the nymph Aegina to Aegina's father, Asopus.
Sisyphus was condemned to Tartarus, the deepest, darkest reality beneath the Underworld, by Zeus. There, he managed to fool Th´natos, the dæmon responsible for death. Sisyphus asked Th´natos to try out his chains to show him how they worked, and when he did, Sisyphus secured him in place.
The consequence of the inprisonment of Th´natos was that mortals could no longer die. This obviously upset the normal order of things, and especially upset Ares, god of war, who could not enjoy his battles when the men he defeated did not die. Ares intervened and released Th´natos.
Sisyphus was deemed guilty of hubris in his belief that he could outsmart the gods, and that he had betrayed Zeus' secret as if it were his place to be involved in the affairs of a god. As punishment, he was condemned to spend eternity rolling a boulder up a hill. Each time the boulder would near the summit, it would roll back down to the bottom. Sisyphus would then be forced to repeat his task.
Note: French writer Albert Camus compares Sisyphus' punishment to the absurdity of the human condition in his essay, “The Myth of Sisyphs”. He famously concludes that despite (or because of) his eternal frustration, “One must imagine Sisyphus happy”.