Who is Aristophanes from Great Dialogues and what is their importance?

Aristophanes is a playwright. He is present at Agathon's dinner party in the "Symposium" and, when it's his turn to deliver a speech, he creates what he acknowledges is a ridiculous myth about the origin of love. According to the myth, humans were originally spheres who rolled around the earth but were split in half when they angered the gods. Love is the impulse which seeks out one's missing half.