Heraclitus of Ephesus (c. 535-c. 475 BCE)Biography (Internet Encyclopedia of Philosophy)
Biography (Stanford Encyclopedia of Philosophy)
Empedocles of Acragas (c.490-c. 430 BCE)Biography (Internet Encyclopedia of Philosophy)
Biography (Stanford Encyclopedia of Philosophy)
Democritus of Abdera (c. 460-c. 370 BCE)Biography (Stanford Encyclopedia of Philosophy)
Biography (Internet Encyclopedia of Philosophy)
Thales: https://commons.wikimedia.org/wiki/File:Thales_1825_at_Alex._Onasis_Foundation.jpg
Heraclitus: http://tr1besman.blogspot.com/2012/03/heraclitus-of-ephesus-impermanence.html
Empedocles: By D. Cunego, 1785, after Raphael. Public Domain. Wikimedia Commons
Democritus: https://commons.wikimedia.org/wiki/File:Democritus2.jpg
Pythagoras Of Samos (c. 570- c. 495 BCE)Biography (Internet Encyclopedia of Philosophy)
Biography (Stanford Encyclopedia of Philosophy)
Parmenides of Elea (Born c. 515 BCE)Biography (Internet Encyclopedia of Philosophy)
Biography (Stanford Encyclopedia of Philosophy)
Pythagoras: Public domain. Source
Parmenides: http://www.philosophybasics.com/philosophers_parmenides.html
Protagoras: https://commons.wikimedia.org/wiki/File:Euripides_Pio-Clementino_Inv302.jpg
Diogenes: Detail from the School of Athens by Raphael. Public domain. Wikimedia Commons
Thales of Miletus (c. 624-c. 546 BCE)
Protagoras of Abdera (c. 490-c. 370 BCE)
Diogenes of Sinope (c. 412-c.323 BCE)