Socrates
Although Socrates (470-399 BCE) is the central figure of these dialogues, little is actually known about him. He left no writings, and what is known is derived largely from Plato and Xenophon.
Socrates was a stone cutter by trade, even though there is little evidence that he did much to make a living. However, he did have enough money to own a suit of armor when he was a hoplite in the Athenian military. Socrates' mother was a midwife. He was married and had three sons. Throughout his life he claimed to hear voices which he interpreted as signs from the gods.
It appears that Socrates spent much of his adult life in the agora (or the marketplace) conversing about ethical issues. He had a penchant for exposing ignorance, hypocrisy, and conceit among among his fellow Athenians, particularly in regard to moral questions. In all probability, he was disliked by most of them.
However, Socrates did have a loyal following. He was very influential in the lives of Plato, Euclid, Alcibiades, and many others. As such, he was associated with the undemocratic faction of Athens. Although Socrates went to great lengths to distinguish himself from the sophists, it is unlikely that his fellow Athenians made such a distinction in their minds.
Socrates is admired by many philosophers for his willingness to explore an argument wherever it would lead as well as having the moral courage to follow its conclusion.