What was the name of the seat at the Round Table reserved for the perfect knight?

The seat at the Round Table reserved for the perfect knight was the Siege Perilous.

In Arthurian romance, the Siege Perilous is a vacant chair set aside for the knight destined to achieve the Holy Grail. Merlin establishes or protects the seat, and tradition warns that an unworthy knight who occupies it will die. Its danger is therefore spiritual as well as physical: the chair tests whether a knight possesses the exceptional purity required by the Grail quest.

In the Lancelot-Grail cycle and Thomas Malory’s Le Morte d’Arthur, Sir Galahad is the knight who finally takes the seat. He arrives at Arthur’s court on Whitsunday, and the previously empty place bears a sign identifying it as his. Earlier stories gave the dangerous-seat motif to Perceval, showing how Arthurian roles shifted between texts.

A common mix-up comes from the word “siege.” Here it derives from Old French terms for a seat or throne, not from military encirclement. The phrase therefore means the “perilous seat,” not a siege of Camelot.