Black Knight

The Black Knight appears only in the Minish Cap, in Dark Hyrule Castle. The Black Knight is actually a Darknut, only it has enhanced endurance and strength, and recovers from attacks and blocks much quicker than other regular Darknuts. It still features the same attacks as the other darknuts in the Minish Cap. Link encounters the Black Knight twice, once as the sub-boss of Dark Hyrule Castle, and again, along with two Royal Darknuts, to attempt to stop Link from interrupting Vaati's ritual. After completing the game, Link can get a trophy in the Minish Cap for the Black Knight.

Quote from The Legend of Zelda: The Minish Cap Black Knight figurine: "Appears in Dark Hyrule Castle. This is the strongest Dark Nut, with a good balance of attack and defense. They will do anything to stop you."