Gawain
From The Stargate Omnipedia
A knight of the Round Table who is said to have gone on a quest to help search for a lost love. He is likely a human from Earth, on whom the myth of Sir Gawain was based. Legend says that Gawain (also known as Gaukamain) visited several distant lands including Gwlad Gan Brenhinol Gwir -- Welch for "The Land of Royal Truth." If this phrase is translated into Ancient, the answer is "Verus Gen Bree," or Vagonbrei.
In reality, Sir Gawain visited the planet Vagonbrei through the Stargate. Whether he was searching for his lost love, or among those with Arthur who searched for the Sangraal, is not known.
KEY EPISODE
Morpheus - Daniel discovers references to Vagonbrei through the legend of Sir Gawain.