Hades, God of the Underworld and brother to Zeus and Poseidon.
It’s tough to avoid being cast as the villain in every Greek/Roman themed story ever when you’re associated almost exclusively with death. Ominously dubbed “Host of Many” by Homer, (for we will all be his guest, eventually) Hades was given the crappy 1/3 of the world when Zeus divvied it up between his brothers. Perhaps his most famous exploit, the kidnapping and tricking of Persephone, also provides the aetiological explanation for the turn of the seasons:
When Demeter, the mother of Persephone and Goddess of Agriculture and Fertility found out what’d happened to her daughter, she gave in to despair and let the earth dry up, and crops die. Persephone was eventually given the right to spend 2/3 of every year with her mother, but forced to spend the final 1/3 in the Underworld, as Hades’ wife. When Persephone was with her mother, Demeter was happy, and crops thrived (Summer/Spring). The rest of the time, Demeter was empty and sad (Winter).
Hades doesn’t even get a full-time wife. He’s stuck in the underworld, every hero makes him look like an idiot, and, oh: he’s infertile. Poor guy.