DWIGHT: I was in a terrible marriage, you know … Oh, yeah, horrible, like a punishment out of Greek mythology. The woman had five heads, suffering, agony.
Greek mythology features an impressive list of some extremely cruel punishments doled out to humans by the gods. The Titan Atlas had to hold up the heavens on his shoulders for all eternity, King Sisyphus had to roll a boulder uphill for all eternity, only for it roll back the second he managed it, Tantalus had to spend eternity surrounded by food and drink without being allowed one mouthful of either, and Prometheus was chained to a rock while an eagle pecked at his liver, which regrew each night so it could start again the next day.
The comment about Dwight’s wife having five heads probably refers to the number of multiple-headed monsters in Greek mythology. The Hydra was a giant nine-headed water serpent, Typhon was a terrible monster with one hundred dragon’s heads, and Cerberus, who guarded the gates of the Underworld, was a monstrous dog with at least three heads, although possibly as many as fifty.