Grimm (Hollow Knight)

"Through dream I travel, at lantern's call, to consume the flames of a kingdom's fall."

- Grimm's riddle in the Hunter's Journal.

Grimm, also known as the Nightmare King, is a supporting antagonist in Hollow Knight, introduced in "The Grimm Troupe" DLC. He is the leader of the mysterious Grimm Troupe, a cult of street performers who seek to devour the flames of the fallen kingdom of Hallownest, and manipulates the Knight into helping him succeed with his ritual.

History
Grimm first appears when the Troupe is first summoned to Hallownest by the Knight lighting up a flame in a hidden area in the Howling Cliffs, after which they set up camp in Dirtmouth. Inside the main tent is Grimm, where he greets himself to the Knight and explains his desires to gather the flames of his kin to claim the dying kingdom for himself and influences the Knight to help him with his plan. He gives him the Grimmchild charm, and encourages the Knight to seek and defeat the three Grimmkin who have gather flame to upgrade their Grimmchild.

After defeating the three Grimmkin and collecting their flames, Grimm summons the Knight and the Grimmchild back to his tent and uses the flames to upgrade Grimmchild into a deadly companion. He then sends the Knight out to find three more flames to further grow the Grimmchild so he can begin the performance. Following the next three flames, Grimm leads the Grimmchild into his body and challenges the Knight. After defeat, Grimm gives the Knight a charm notch and returns the Grimmchild, now at its third form, and encourages the Knight to seek out the last three flames so the grand performance could begin.

Following Grimm's boss fight, the player is given two options: first is to collect the remaining three flames and return to Grimm, where he is now resting. Dream Nailing him takes the Knight to Grimm's dream, where they must fight against Nightmare King Grimm to complete the performance and finish the ritual. Defeating him will grant the Knight the fourth and final form of the Grimmchild, although Grimm and the rest of his Troupe will vanish (although Divine will stay behind and upgrade the fragile charms).

However, talking with Brumm in the Deepnest before collecting all three flames and following him to Howling Cliffs to quench the first flame ever ignited will cancel the ritual and banish the troupe. This undoes Grimm's ritual, leading to the disappearance of the troupe as if they never came to Hallownest.

Appearance
In his regular appearance, Grimm is a slender dark being covered by a multicolored cloak, with a gray exterior and a red interior. His face is pale with red eyes, and underneath his cloak, his body is scaled and purple. As the Nightmare King, Grimm’s body turns entirely red, with the exception of his face, which remains tan, and his limbs remain black.

Trivia

 * Grimm, especially his Nightmare King form, is based on vampires, most notably Dracula.
 * At the beginning of the battle, if Grimm is attack while he is bowing, he lets out a banshee screech and retaliates with his Flame Spawner attack, which he normally doesn’t use until he is halfway defeated.
 * The Grimmchild charm is required for both battles.
 * The audience in the background applauds every time Grimm uses his Fire Spawner attack and reforms after being staggered.
 * Nightmare King Grimm is tied with the White Defender as having the second highest health of any boss in the game, behind The Radiance.
 * Along with the Radiance, Nightmare King Grimm has a fullscreen title card.
 * With his very fast moveset with hard to dodge attacks, all of which deal two masks of damage, Nightmare King Grimm is widely considered the hardest boss in the entire game.