The Radiance

"The light, forgotten. The plague, the infection, the madness that haunts the corpses of Hallownest... the light that screams out from the eyes of this dead Kingdom. What is the source? I suppose mere mortals like me will never understand."

- Hunter's Guide

The Radiance is the main antagonist and true final boss of the 2017 video game, Hollow Knight.

A powerful and destructive entity, the Radiance is the being responsible for creating the bugs of Hallownest, but punishes

Appearance
The Radiance resembles a white moth with multiple gray tentacles by its side that act as wings. It has yellow glowing eyes, a black face, and three spear-like spikes creating a crown. Its legs appear to be made up of two appendages.

History
At one point in the past, a supreme being created a race of highly intelligent moths known as Wyrms to build an empire, but at the cost of keeping them connected as a hive mind. The Wryms came to worship the being, referring it as "The Radiance", but over time came to respect the new king of the empire, the Pale King of Hallownest. The Pale King used a substance known as Void he obtains from an abyss to create all sorts of inventions, granting all of his followers to live in permanent peace.

The Radiance, upon realizing that all of its creations have turned against it by obtaining free will and evolving at their own pace, punished its traitors by entering their minds and drained all of their memories away until their mind is nothing but a horrible, raging light. While some are killed by this transaction, the rest are turned into living emotionless zombies, starting "The Infection". To save his endangered kingdom, the Pale King created multiple living containment vessels out of beings from the void called Slades to seal away the Radiance, though most of them resulted in failures. The second to last vessel created eventually succeeds in sealing the Radiance inside it and takes shelter in a giant cocoon referred as the Black Egg, eventually earning the title "The Hollow Knight". The last vessel, the player character, takes shelter in a deserted location and falls into a deep slumber, with their primary purpose already fulfilled.

However, as the kingdom recovers following the Infection, the Radiance's presence returns through the Black Egg as its magic begins to wither and the Infection returns, despite the King's best efforts to contain the contagion. Soon, the King and all of the remaining Wyrms disappear and the Hallownest collapses into despair. Several years later, the player, sensing the return of the Infection, awakens from their slumber and sets off to confront the Hollow Knight and stop the Radiance from destroying the rest of the Hallownest.

Endings
Depending on the player's progress through the game, three different endings can occur:

The Hollow Knight: The player defeats three infected Dreamers protecting the Black Egg and enters inside it, freeing the Hollow Knight from the chains connecting it to the Egg, where it will then attack its younger sibling. The player eventually defeats the Hollow Knight and absorbs the plague from the Hollow Knight, before getting sealed inside the Black Egg as the new container for the Infection.

Sealed Siblings: To obtain this ending, the player must achieve two important objectives: awaken their Dream Nail by defeating every ghost of fallen plague heroes throughout the map and use their Dream Nail to retrieve the Void Heart at the end of the Abyss. During the final moments with the Hollow Knight fight, Hollow, another Vessel that the player befriends throughout the game will join in an temporarily stun the Hollow Knight, allowing the player to use the Dream Nail on the Hollow Knight to enter its dream. If the player chooses to attack the Hollow Knight with any other weapon or waits too long without using the Dream Nail, the Hollow Knight will break out of its stun, killing Hornet, and continues its brawl against the player until its death. Much like the regular ending, the player becomes the new container for the plague, this time getting sealed into the Black Egg alongside Hornet. With Hornet gone, there is no longer a way how to stop the Infection for good.

Dream No More: This ending requires the same requirements as the Sealed Siblings ending, but only if the player attacks the Hollow Knight with the Dream Nail as Hornet holds it down. This will summon the player to the Hollow Knight's dream, where the player will engage the Radiance in a one on one fight to the death. As the Radiance takes damage, the Void, along with shades of the fallen vessels and even the shade of the Hollow Knight itself, flow into the dream world and eventually corner the Radiance. The player sacrifices their physical body and becomes a shade to join their siblings in dragging the Radiance into the Void, finally killing it and ending the Infection once and for all. The remaining shades return to the Void with their purposes fulfilled, although Hornet stays behind to help the Hallownest return to its original glory.

Trivia

 * The Radiance is not required to complete the Hunter's Journal, despite having an entry.
 * The Radiance is one of the two bosses that must be challenged to battle, the other being the Mantis Lords. While the Mantis Lords will have to be challenged every time, the Radiance will attack the player directly upon entering the arena following the first attempt.
 * If inflicted with the Dream Nail, the Radiance lets out dialogue:
 * "...ANCIENT ENEMY..."
 * "...I DO NOT FEAR YOU..."
 * "...LET ME BE FREE..."
 * "...I WILL NOT BE FORGOTTEN..."
 * "...DAWN WILL BREAK..."
 * "...THE LIGHT CANNOT BE CONSUMED..."
 * The Radiance shares similarities with Bill Cipher from Gravity Falls.
 * Both are psychic entities who can enter and possess minds.
 * Both have unlimited powers.
 * Both met their demises whilst inside an possessed mind (Bill was destroyed in Stanley's mind while the Radiance was destroyed in the Hollow Knight's mind).