Euthyphro

Euthyphro of Prospalta (Εὐθύφρων Προσπάλτιος) was an ancient Athenian religious prophet (mantis) best known for his role in his eponymous dialogue written by the philosopher Plato, which tells of Euthyphro's encounter with the aged Socrates, sometime between 404 and 399 BC. Euthyphro, who professes extreme piety, tells Socrates that he intends to prosecute his own father, who is accused of murder, because the gods' law demands it. Seeking to learn the meaning of the word "piety", Socrates asks Euthyphro a set of rhetorical questions about the gods and their laws. One of these questions is known as the "Euthyphro dilemma" or "divine command theory of morality", and has been debated by generations of theologians, who have applied it to the monotheistic God rather than the polytheistic Ancient Greek gods. It is usually worded as "Do the gods command something because it is good, or is something good because the gods command it?"

As Euthryphro's life is wholly undocumented outside of Plato's writing, he may or may not have actually existed.

Euthyphro in "The Daimon"
Euthyphron was an Athenian hoplite taking part in Alkibiades' invasion of Sicily. While waiting in a chow line, Euthyphron discussed important matters of faith with another hoplite, Sokrates, who claimed to be very simple, and hoped that Euthyphron could help him understand this complicated logic. Sokrates asked "Do you say deeds are unholy because the gods hate them, or do you say the gods hate them because they are unholy?" Euthyphron replied "I certainly do," and a third man pointed out that it was a question of one or the other, and that Euthyphron could not have it both ways. Euthyphron tried to have it both ways anyway, but Sokrates' questions wouldn't let him. Euthyphron was so dazed and confused that he left the chow line without being served. When another hoplite accused Sokrates of tying Euthyphron up in knots, Sokrates replied that Euthyphron's thinking was already not straight, and that hopefully Sokrates' questions could help Euthyphron root out the truth.