Greek mythology is full of stories about justice and vengeance. More often than not, the gods dealt with the transgressions of mere mortals by serving punishments that far outweighed the misdeeds. Hera's anger about her husband's illegitimate son, Hercules, for example, led her to send two snakes to destroy him (she didn't succeed). Still, there are a few satisfying revenge stories in Greek mythology.
The most justified punishments doled out by mythological characters are often a result of someone's extreme arrogance, infidelity, or attempt to eat their own children.
In Homer's The Odyssey, the Trojan conflict took Odysseus from his home for 20 years. He left behind his new bride, Penelope, and in his absence many men came asking for Penelope's hand, as they believed Odysseus had passed. Over the years, Penelope avoided marriage, but her suitors had a habit of hanging around her palace and eating dinner, attempting to woo her, and feeding their scraps to a beggar.
Eventually, her suitors concluded Penelope was toying with their emotions and demanded she choose. Penelope devised an archery contest she deemed unwinnable in return for her hand.
The suitors all failed, but the final man, the beggar, was able to complete the challenge perfectly. He took out each of the suitors with an arrow before revealing himself as Odysseus, having finally returned for his wife.
The son of Zeus and a nymph, Tantalus was allowed to regularly visit and dine with the gods on Mount Olympus. In his arrogance and hubris, Tantalus took nectar and ambrosia from Mount Olympus in the hopes of discovering the secrets of immortality and divinity. Tantalus then served his son, Pelops, for dinner.
The gods refused to eat the mortal meat, and Zeus brought the boy back to life and banned Tantalus from Mount Olympus. When Tantalus passed, he was cursed to stand in a shallow pool under a fruit tree for all eternity. Whenever Tantalus tries to reach for fruit, the branches grow just out of his reach and the water in the pool recedes.
Nemesis is a goddess with wings who represents justice and revenge. Her name means "dealer of proportional fortune," and she gets particularly aggravated by mortals who appear arrogant before the gods. Narcissus, a beautiful young mortal man, was self-obsessed and disdainful. Echo the nymph, cursed by Hera to repeat the words of others, fell in love with Narcissus, but he rebuffed her advances.
When Nemesis learned of this, she led the arrogant man to a pool where he became enamored with his own face staring back at him. She cursed Narcissus to live the rest of his days looming over the pool, unable to abandon his beloved reflection.
Cronus was the youngest of the 12 titans, best-known for swallowing his children - Hestia, Demeter, Hera, Hades, and Poseidon - to thwart a foretelling of his offspring overthrowing him. When his wife/sister Rhea bore Zeus, she hid the child and gave Cronus a rock to swallow instead.
As an adult, Zeus forced Cronus to regurgitate his brothers and sisters, and he clashed with his father, eventually defeating him and taking control.