Did King Arthur really exist?
Probably not. Historians have searched for actual people who could have been the model for Arthur, but there is no record of one king accomplishing all that the Arthurian legend ascribes to Arthur. Again, the tales and deeds of Arthur and his knights changes based on the author, and more importantly, the time period of the author and his intended audience.
However, historians still search for actual figures whose deeds could have inspired the legends of King Arthur.
Here are a few attempts.
Lucius Artorius Castus, and more
Owain Ddantgwyn and King Arthur in Shropshire
Arthur from Timeless Myths
Arthur, King of the Britons and everyone else
Mythical basis for King Arthur
Historical Arthur
Ambrosius Aurelianus, historical figure and Arthur's uncle?
Britannica
A Timeline of history and Arthurian events
Another timeline, with links
However, historians still search for actual figures whose deeds could have inspired the legends of King Arthur.
Here are a few attempts.
Lucius Artorius Castus, and more
Owain Ddantgwyn and King Arthur in Shropshire
Arthur from Timeless Myths
Arthur, King of the Britons and everyone else
Mythical basis for King Arthur
Historical Arthur
Ambrosius Aurelianus, historical figure and Arthur's uncle?
Britannica
A Timeline of history and Arthurian events
Another timeline, with links