5. Xenophanes
Xenophanes is from Colophon and was a traveling poet. This is a stretch to call him an atheist. However, he is best known as a critic of religion. He especially was critical of the popular notions of deities at the time. However, some also argue now that he was a monotheist while others have views that he was a pantheist.
“The clear and perfect truth no man has seen, nor will there be anyone who knows about the gods and what I say about all things…; for, however, perfect what he says may be, yet he does not know it; all things are matters of opinion.”