The Five Great Knights

"Mighty Hegemol... What a towering figure he was, though surprisingly soft spoken for one so large.

'They were all impressive in their own right, of course. Fierce Dryya, kindly Isma, mysterious Ze'mer ... erm, and the other one." - Nailmaster Sheo'Five legendary figures once stood beneath the throne as the kingdom's protectors. Their names are long forgotten, and they must surely have died with their Age.

The Five Great Knights are often mentioned and they must have played an important role in Hallownest before the infection.

As of the events of the game, only Ogrim (Dung Defender) and Ze'mer (Grey Mourner) are known to be alive.

The Five Great Knights are:
 * Fierce Dryya
 * Kindly Isma
 * Mysterious Ze'mer
 * Loyal Ogrim
 * Mighty Hegemol

The Great Knights are depicted in the Dung Defender's secret room as statues made of dung, along with a statue of the King:

From left to right: Hegemol, Ze'mer, Dryya, Isma, Ogrim and the Pale King Their silhouettes can be seen in the arena where the player fights the White Defender:

From left to right: Hegemol, Ze'mer, Dryya, Isma and the Pale King

Fierce Dryya
''"One of Hallownest's five greatest Knights and defender of the Queen’s Glade. She was driven mad by her Queen lost and the garden overrun. Still she retains her honour, offering fair challenge to the Hollow Knight: Nail against nail. A duel to the death." - Official Kickstarter Update''

Unfortunately Dryya did not make it into the game alive. Her corpse is found in front of the White Lady's hiding place in the Queen's Gardens, surrounded by the corpses of Mantis Traitors, which implies that she died defending her Queen. The White Lady however, is seemingly unaware of this.

Kindly Isma
Isma's body is found in Isma's Grove and is only accessible after draining the acid after defeating the Dung Defender. Both their dialogue, as well as a note hung outside of her Grove, suggest that they had a very close relationship. From his dialogue, Dung Defender does not seem to be aware of her death.

Mysterious Ze'mer
Most likely the Grey Mourner due to her resembling the Dung Defender's statue and the silhouette in the White Defender's arena, as well as the way she speaks; she refers to the player as "le'mer" which is very similar to "Ze'mer." She also has a large Nail in her home and comments about serving the King when shown the King's Brand. However, while other NPCs who know about such things tend to comment on the player wearing the Defender's Crest, the Grey Mourner has no such dialogue.

Loyal Ogrim
"Deep in the Waterways beneath the City of Tears lurks a shunned being. Once a knight, now lost to puerile obsession: The Dung Defender.

Despite his exile, the Dung Defender has for centuries maintained a self-conferred charge: the protection of his mysterious gleaming 'beloved.'

Stalwart and full of bravado, the Dung defender eagerly challenges all who would enter his noxious realm."- Official Kickstarter

Found in the Royal Waterways, defending Isma's Grove from those overtaken by the infection. Outside of Isma's Grove, a sign reads:

"Only those who prove their honour in combat may enter the grove beyond. - The Defender"

When struck with the Dream Nail as he is sleeping, he can be seen in a recreation of his past life as the White Defender.

Mighty Hegemol
Not much is known of the Mighty Hegemol or his whereabouts. His armour was stolen by a maggot as to defend its brothers. It is unknown whether or not he is alive. While the False Knight wields a mace with an armoured bug attached to the end, it is unknown if Hegemol used the same weapon. According to Nailmaster Sheo, he was a "towering figure, though surprisingly soft spoken for one so large," and one of the White Defender's lines references his "jokes." A statue of him can be found outside the City of Tears, requiring the City Crest to open the gate to the city.

Trivia
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 * In the Kickstarter campaign, it was stated that all five Great Knights were intended to be bosses of some type, but was dropped in the full release for unknown reasons.
 * With the Hidden Dreams DLC, White Defender appearing in white armour implies that all five of the Great Knights most likely dressed in white while serving the King.
 * Based on in-game files, Hegemol was originally the name of The Beast, later renamed to Herrah.