The Knights (Ancient Greek: Ἱππεῖς) is a comedy by Aristophanes which won first prize at the Lenaea festival at its first performance in Athens in 424 BC. It is effectively an allegory in which the the old man Demos represents the Athenian people, while his slaves Demosthenes and Nicias represent prominent generals. The latter are tormented by a new slave, 'the Paphlagonian', who flatters their master, in a satirical reference to the popular politican Cleon.
Free online texts
Internet Archive: Aristophanes I - Acharnians, Knights, Clouds, Wasps. Greek text and English translation. Public domain Loeb edition, multiple formats.
Internet Classics Archive: The Knights. HTML and TXT formats.
Loebulus: Aristophanes I: Acharnians. Knights. Clouds. Wasps. PDF of public domain Loeb edition.
Poetry in Translation: Knights, translated by George Theodoridis. Multiple formats.
University of Adelaide (Internet Archive): The Knights. English translation, HTML format.
The Great Conversation: Further reading at Tom's Learning Notes
Thucydides - Our best source for the political events which provided the occasion for Aristophanes' satire, although one which took a similarly jaundiced view of Cleon's career.
Ancient Greek resources: Learn to read Greek classics in the original.
Bloom's Western Canon: The Knights is listed.