Arthur himself did not even set off on the Quest for the Holy Grail. Depending upon which version you're reading the successful knight is either Percival or Galahad, a few others are listed as being there as well. So Arthur did not complete the Quest.
Arthur himself never found the grail. Galahad was the purest, so he could find the grail. Percival and another also saw the cup.
he was charged by God to find it
to restore the holy kingdom
win him and his knights honor
In Chrétien de Troye's Perceval ou la Conte del Graal, the earliest extent graal romance, only Perceval and Gawain are shown to be searching for the grail. In this and most other romances the quest is primarily Perceval's personal quest. However increasingly the grail quest is seen is the central exploit of the Arthurian era. In the Prose Perceval which claims to be by Robert de Boron, when Perceval achieves the grail, that is the general end of wonderful adventures in Arthur's realm. Arthur subsequent conquest of Gaul which leads to a war with Rome is explained as an attempt to keep his knights interested by providing them with feats worthy of their valor.The prose romance Perlesvaus has Perceval, Gawain, and Lancelot all seeking the grail. And it is explained that Percveval's failure to ask the question when he first came to the grail castle has resulted in the illness of the grail king and general lethergy across all of Brtain. Even King Arthur has been affected. In the original Vulgate Arthur Cycle, consisting of the Prose Lancelot, The Quest of the Holy Grail, and The Death of Arthur, it is explained that Arthur's kingdom is afflicted with many difficult adventures, many of which are adventures of the grail. Only a promised best knight will achieve the most difficult of these adventures. Meanwhile the Knights of the Round Table do achieve many of the lesser adventures and put an end to the oppression they cause. Here first comes that idea that all Arthur's Knights of the Round Table take part in the quest of the grail.After the grail quest is achieved by Galahad, Perceval, and Bors there are no more wonderful adventures.
Sir Lancealot was famous in Arthurian legend as one of the knights in King Arthur's Round Table. He is renowned for being both the worst and best knight in King Arthur's court. He was part of the unsuccessful quest for the Holy Grail and pulled Guinevere into temptation and put to death for adultery with him.
Richard the Lionheart fought against Saladin and other Muslim warriors to recapture the holy land of Jerusalem. His allies were Emperor Frederick and King Philip I. Although Richard fough against Saladin bravely he was forced to leave Jerusalem in the hand of Saladin.
He was the Grail Knight, the only knight able to sit in the Siege Perilous, a seat at the Round Table where only one knight could sit or they would die. He was pure, courageous, chivalrous, courteous, gentle and kind. He was the son of Elaine of Corbenic and Lancelot, and was the only Knight able to drink from the Holy Grail, the cup that Jesus supposedly drank from at the Last Supper.
Only the pure in heart can find the holy grail.
The chalice in King Arthur's tails was the Holy Grail.
In some versions of the legend, King Arthur and his knights search for the Holy Grail, but finding it is often left ambiguous or open to interpretation. The quest for the Holy Grail is a central theme in Arthurian legend but the outcome varies across different versions of the story.
King Arthur on one of his many quests
He set his Knights of the Round Table the quest to find the Holy Grail.
he was one of king Arthur's nights who found the holy grail
Sir Galahad's quest was to find the holy grail
win him and his knights honor
Sir Bedevere
The story goes that they were looking for the Holy Grail.
King Arthur, Merlin, the Knights of the round table, Camelot and the Holy Grail.
Galahad, Bors the Younger, and Percival achieve the Grail... source: http://en.wikipedia.org/wiki/Bors