Pendragon is a role-playing game inspired by Arthurian literature, primarily Sir Thomas Malory's Le Mort D'Arthur. Players take on the role of knights, with much of the game based around knightly values and activities: quests, combat, battles and courtly romance and intrigue.
The system is a variant on Chaosium's Basic Role Playing (both games were written by Greg Stafford). The first through third editions were published by Chaosium, the 4th Edition by Chaosium and then Green Knight Publishing, and the new 5th Edition is published by White Wolf. For more detail, see the Wikipedia article.