Sir Gawain was one of of King Arthur's Knights of the Round Table.
More information may be found in this Wikipedia article about Sir Gawain.
Gawain is King Arthur's nephew and a Knight of the Round Table in the Arthurian legend of ancient Earth. He is the son of Arthur's sister Morgause and King Lot of Orkney, and his brothers are Agravain, Gaheris, Gareth, and Mordred. According to some legends, he would have been the true and rightful heir to the throne of Camelot, after the reign of King Arthur. Gawain is often portrayed as a formidable, courteous, and also a compassionate warrior, fiercely loyal to his king and family. He is a friend to young knights, a defender of the poor, and of women. For this last he earned the sobriquet "the Maidens' Knight". Sir Gawain is most famous as the hero of the tale, Sir Gawain and the Green Knight. In it Sir Gawain accepts a challenge from a mysterious "Green Knight" who challenges any knight to strike him with his axe, stating that all such blows would be returned in kind, in a year and a day. Gawain accepts and beheads him with his blow, at which the Green Knight stands up, picks up his head and reminds Gawain of the appointed time. In his struggles to keep his bargain Gawain demonstrates chivalry and loyalty until his honor is called into question by a test involving Lady Bertilak, the lady of the Green Knight's castle.
The motto of the HMS Gawain is Omnes Ictus Tunc Rehabebunt, "All Blows Shall Be Returned"; its crest is a stylized double-headed eagle bearing upon itŐs chest the arms attributed to Sir Gawain. Purpure a double headed eagle displayed Or.