Gareth is a boy’s name of Anglo-Saxon, Arthurian Legend and Welsh origin. Meaning in Anglo-Saxon: Strong spear. Meaning in Arthurian Legend: Gentle. Gareth was a knight of the Round Table portrayed in both Sir Thomas Malory’s and Tennyson’s versions of the Arthurian legend. Also a son of Lot. Meaning in Welsh: Gentle. Modest and brave Sir Gareth was a legendary knight of King Arthur’s Round Table. The name has 6 letters.