The Sword in the Stone - an animated Disney movie that popularized the story of the young King Arthur pulling the sword from the stone

The Once and Future King - the most popular retelling of the Arthurian legends, by T.H. White

Camelot - a musical based on The Once and Future King, also a classic movie

Monty Python and the Holy Grail - a comical retelling of the quest for the Holy Grail which draws heavily on various archetypes such as the knight who won't give up the battle and the dangerous beast in disguise

Indiana Jones and the Last Crusade - a classic swashbuckler movie about archaeologist Indiana Jones and his own quest to find the Holy Grail (and defeat the Nazis along the way)

The Mists of Avalon - a retelling of the whole of Arthurian legend from Arthur's parents' lives through to after his death, told from the women's point of view, by Marion Zimmer Bradley; more recently made into a TV miniseries

Merlin - a movie about the mysterious, mystical mage Merlin

Excalibur - a movie about the famous sword Excalibur

King Arthur - another movie, this time drawing on the history of [Hadrian's Wall]

Tristan & Isolde - both an opera by Wagner and many, many movies (including one from 2006), this story ties in tangentially with Arthurian legend through King Mark

The Dark is Rising sequence - a series of five books by Susan Cooper that plays on stories of the Holy Grail, Merlin and other Arthurian legend

And these are only a handful of the countless retellings of Arthurian legends...