Tall Knight in the Palfrey's Garden

When the Haughty Maid of Logres sent Gawaine across the river into the garden for her Little Piebald Palfrey, he found a tall knight sitting there beneath an olive tree, quietly looking on. This knight warned Gawaine that every previous knight who had taken the palfrey had lost his head for his pains.

Not that the Tall Knight would himself lift a finger to fight Gawaine - which might have surprised medieval audiences as much as modern readers. No, for all his size and knighthood, he simply acted as a sort of human warning sign.