Question: What classical Greek philosopher credited as one of the founders of Western philosophy, was featured in the Socratic dialogue, The Symposium? 

Context paragraphs:
Symposium: In ancient Greece, the symposium (Greek: συμπόσιον "symposion", from συμπίνειν "sympinein", "to drink together") was a part of a banquet that took place after the meal, when drinking for pleasure was accompanied by music, dancing, recitals, or conversation.  Literary works that describe or take place at a symposium include two Socratic dialogues, Plato's "Symposium" and Xenophon's "Symposium", as well as a number of Greek poems such as the elegies of Theognis of Megara.  Symposia are depicted in Greek and Etruscan art that shows similar scenes.

Socratic dialogue: Socratic dialogue (Ancient Greek: Σωκρατικὸς λόγος ) is a genre of literary prose developed in Greece at the turn of the fourth century BCE.  It is preserved in the works of Plato and Xenophon.  The discussion of moral and philosophical problems between two or more characters in a dialogue is an illustration of one version of the Socratic method.  The dialogues are either dramatic or narrative and Socrates is often the main participant.

Socratic method: The Socratic method, also can be known as maieutics, method of elenchus, elenctic method, or Socratic debate, is a form of cooperative argumentative dialogue between individuals, based on asking and answering questions to stimulate critical thinking and to draw out ideas and underlying presumptions.  It is a dialectical method, involving a discussion in which the defense of one point of view is questioned; one participant may lead another to contradict themselves in some way, thus weakening the defender's point.  This method is named after the Classical Greek philosopher Socrates and is introduced by him in Plato's Theaetetus as midwifery (maieutics) because it is employed to bring out definitions implicit in the interlocutors' beliefs, or to help them further their understanding.

Statesman (dialogue): The Statesman (Greek: Πολιτικός , "Politikos"; Latin: "Politicus"), also known by its Latin title, Politicus, is a Socratic dialogue written by Plato.  The text describes a conversation among Socrates, the mathematician Theodorus, another person named Socrates (referred to as "Young Socrates"), and an unnamed philosopher from Elea referred to as "the Stranger" (ξένος , "xénos").  It is ostensibly an attempt to arrive at a definition of "statesman," as opposed to "sophist" or "philosopher" and is presented as following the action of the "Sophist".

Symposium (Xenophon): The Symposium (Greek: Συμπόσιον ) is a Socratic dialogue written by Xenophon in the late 360's B.C.  In it, Socrates and a few of his companions attend a symposium (a lighthearted dinner party at which Greek aristocrats could have discussions and enjoy entertainment) hosted by Kallias for the young man Autolykos.  Xenophon claims that he was present at the symposium, although this is disputed because he would have been too young to attend.  The dramatic date for the "Symposium" is 422 B.C.

Gorgias (dialogue): Gorgias ( ; Greek: Γοργίας ) is a Socratic dialogue written by Plato around 380 BC.  The dialogue depicts a conversation between Socrates and a small group of sophists (and other guests) at a dinner gathering.  Socrates debates with the sophist seeking the true definition of rhetoric, attempting to pinpoint the essence of rhetoric and unveil the flaws of the sophistic oratory popular in Athens at the time.  The art of persuasion was widely considered necessary for political and legal advantage in classical Athens, and rhetoricians promoted themselves as teachers of this fundamental skill.  Some, like Gorgias, were foreigners attracted to Athens because of its reputation for intellectual and cultural sophistication.  In the "Gorgias", Socrates argues that philosophy is an art, whereas rhetoric is a skill based on mere experience.  To Socrates, most rhetoric is in practice merely flattery.  In order to use rhetoric for good, rhetoric cannot exist alone; it must depend on philosophy to guide its morality, he argues.  Socrates therefore believes that morality is not inherent in rhetoric and that without philosophy, rhetoric is simply used to persuade for personal gain.  Socrates suggests that he is one of the few Athenians to practice true politics (521d).

Socrates: Socrates ( ; Greek: Σωκράτης , "Sōkrátēs"; 470/469 – 399 BC) was a classical Greek (Athenian) philosopher credited as one of the founders of Western philosophy.  He is an enigmatic figure known chiefly through the accounts of classical writers, especially the writings of his students Plato and Xenophon and the plays of his contemporary Aristophanes.  Plato's dialogues are among the most comprehensive accounts of Socrates to survive from antiquity, though it is unclear the degree to which Socrates himself is "hidden behind his 'best disciple', Plato".

Hipparchus (dialogue): The Hipparchus ( ; Greek: Ἵππαρχος ), or Hipparch, is a dialogue attributed to the classical Greek philosopher and writer Plato.  There is some debate as to the work's authenticity.  Stylistically, the dialogue bears many similarities to the "Minos".  They are the only dialogues between Socrates and a single anonymous companion; they are the only dialogues where the titles bear the name of someone long-dead; and they are the only dialogues which begin with Socrates raising a "what is" question.

Meno: Meno ( ; Greek: Μένων ) is a Socratic dialogue written by Plato.  It appears to attempt to determine the definition of virtue, or "arete", meaning virtue in general, rather than particular virtues, such as justice or temperance.  The first part of the work is written in the Socratic dialectical style and Meno is reduced to confusion or aporia.  In response to Meno's paradox (or the learner's paradox), however, Socrates introduces positive ideas: the immortality of the soul, the theory of knowledge as recollection ("anamnesis"), which Socrates demonstrates by posing a mathematical puzzle to one of Meno's slaves, the method of hypothesis, and, in the final lines, the distinction between knowledge and true belief.

On Virtue: On Virtue (Greek: Περὶ Ἀρετῆς ; Latin: "De Virtute" ) is a Socratic dialogue attributed to Plato, but which is considered spurious.  In the short dialogue, Socrates discusses with a friend questions about whether virtue can be taught.  To answer this question, the author of the dialogue does little more than copy out a few passages from the "Meno" almost word for word.

Supporting paragraphs: Symposium (Xenophon) Socrates
Answer: Socrates