Watcher Knights

The Watcher Knights are supporting antagonists and bosses in Hollow Knight. They are the elite bodyguards of Lurien the Watcher, one of the three Dreamers of Hallownest. Much like the rest of the infected, they have gone feral and have turned against their master and the rest of society.

Biography
When Lurien went in a permanent rest with the other Dreamers to seal the Black Egg Temple to keep the infected Hollow Knight at bay, the Watcher Knights defended the spire that Lurien lived in. Following the Infection's return, only six of the knights were still alive by then and have mysteriously burst from their shells into a swarm of infected flies, now attacking everyone regardless if friend or foe.

Located in the Watcher's Spire in the City of Tears, the Watcher Knights serve as the final trial before the Knight can access Lurien. When the Knight enters the arena, the fly swarm reanimates one Watcher Knight, attacking by slashing its nail, or by curling into a ball, moving across the arena either by rolling on the ground or by bouncing up and down. A few seconds go by before a second knight reanimates, followed by a third once one of the two goes down.

They are immune to Nail attacks while curled in a ball, although Spells can still damage them while they are attacking. Since the Watcher Knights attack in twos for all six, they can be unpredictable in nature as they can move fast while curled and their nails have a long range. Several charms, such as Quick Focus and Stalwart Shell, can help the Knight recover quicker, while Fragile Strength and Shaman Stone can boost their attacks against the Watcher Knights. Defeating all six knights unlocks the doors of the room, granting the Knight access to the top of the Watcher's Spire where Lurien lays rest, and destroying him and the other two Dreamers grants access to the Black Egg Temple.

Trivia

 * Directly left to the arena is a breakable ceiling which reveals a secret room containing the anchoring for a chandelier. Cutting the wire drops the chandelier onto one of the Watcher Knight shells, permanently reducing the number of knights by one.
 * The Watcher Knights are referred to as "Black Knights" in the game's files.
 * Combined, the Watcher Knights have the most health out of every boss, excluding the White Defender, Nightmare King Grimm, and The Radiance.
 * In the Lifeblood update, the Watcher Knight shells have been rearranged.