Beof, Bois, Bos, Booz
The Earl of Oxford under King Arthur.
He accompanied Arthur on the Roman campaign, and was one of the three messengers that Arthur sent to meet with the Roman Procurator Lucius – an effort that resulted in ruin when Gawaine killed a Roman warrior.
In the ensuing battle, Boso managed to capture the Roman leader Petreius Cotta (or Peredur).
He also led a company of soldiers at the final battle at Soissons.
His role is taken by Bors in Malory.
Sources
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155
Brut | Layamon, late 12th century to mid-13th century
Alliterative Morte Arthure | c. 1400