Case Description: Complainant (Rhea) accuses Defendant (Kronos) of cannibalism and child abuse. It was prophesied that Kronos, the Titan king of the gods, would be kicked off his throne by one of his own children. So, every time his wife Rhea popped out a new godling, Kronos ate them. Hestia was the firstborn, so she was first to go down the hatch. Hades, Poseidon, Hera, and Demeter followed after her.
Case Status: Case closed. When her final son Zeus was born, Rhea wrapped up a stone in baby blankets and fed it to Kronos instead. Zeus was raised in secrecy, and when he got old enough, he rescued his brothers and sisters. Some say that he slit his father open, while others say that he made Kronos throw them up. Either way, Hestia was the last to see the light of day again, causing some to call her both the oldest and the youngest Olympian.
Addendum: After this whole fiasco, Zeus and his fellow Olympians launched a full-scale rebellion called the War of the Titans and totally took over the cosmos.