The fourth knight defeated by Gareth in Tennyson. He corresponds to the Red Knight of the Red Lands in Malory, though Tennyson gives him black armor.
He gave a fearsome appearance, adorned with bones, and wearing a skull for a helmet. When Gareth shattered the helmet, however, he discovered that Night was actually an youth, coaxed into his position by his brothers.
Source
Idylls of the King | Lord Alfred Tennyson, 1859-1886