List of pre-Socratic philosophers
Pre-Socratic philosophy developed in ancient Greece during the 6th and 5th centuries BC. The pre-Socratic philosophers include those who preceded Socrates and Plato, though in some cases it is used to describe their contemporaries or later figures who continued pre-Socratic thought. The pre-Socratic philosophers were followed by the classical philosophers, including Socrates, Plato, and Aristotle.
Source: Wikipedia — List of pre-Socratic philosophers (CC BY-SA 4.0)