Critias

Critias was an Athenian aristocrat, writer, and politician of the late 5th century BCE, a relative of Plato and an associate of Socrates. He became the most notorious leader of the oligarchic regime known as the Thirty Tyrants imposed on Athens in 404 BCE, and he was killed in the fighting that overthrew it; he was also a poet and prose author whose works survive only in fragments. Some ancient verses on religion as a human invention are attributed to him.