Demon King Ganondorf
The Menace Unleashed
2500 HP (first phase)
Demon King Ganondorf is the penultimate boss of Tears of the Kingdom. He is encountered at Gloom's Lair, all the way at the bottom of the final passageway deep beneath Hyrule Castle, and is responsible for the Gloom that blankets the Depths and all previous bosses before him. He is the only boss to have two different entries in the Hyrule Compendium, one for his initial phase, and another for his second/third phase.
Tears of the Kingdom
"An evil man who lived long ago in the era of Hyrule's founding. He was imprisoned beneath Hyrule Castle for ages, but the magic weakened, and his power has been steadily growing since. Now he has revived as a threat beyond the knowledge of any. A master of every known weapon, he will not hesitate to crush any foe who stands in his way."
When Demon King Ganondorf is first encountered towards the end of the game, he still resembles his mummified "phantom" self, resting in a nest made of Gloom where his power is being restored. He fully reappears after slamming his fist down into the nest causing a tremendous Gloom eruption, which fully restores his original gerudo form as it was before the game's Imprisoning War. In battle, he will often attack Link with his Gloom Sword, but can at any point switch over to a Demon King's Bow, a Gloom Spear or a Gloom Club. Unlike any previous boss in Breath of the Wild or Tears of the Kingdom, Ganondorf is the only other person capable of executing a Perfect Dodge besides Link, and will perform a counter-dodge if Link Perfect Dodges his attack first. It is recommended to wait for him to dodge your attack, and then perform a Perfect Dodge on his counterattack, which will leave him vulnerable to a Flurry Rush. He has 2500 HP in this phase.
"The fearsome form that Demon King Ganondorf attained after unleashing the power of the secret stone. The ancient sages were no match for him and only barely managed to contain his devastating power. The gloom he produces is a corrosive substance so foul that it can wither anyone who touches it."
When his health bar is depleted, Ganondorf will activate his Secret Stone, transforming his clothes into a glowing red fiery texture, growing his now glowing red hair tremendously long, and restoring his health bar, extending it all the way to the edge of the screen, effectively doubling its max. This massive health bar contains 5000 HP, though there is a stopper halfway through (where normal healthbars stop), effectively creating 2 more phases with 2500 HP each. A pool of gloom now follows him almost everywhere he navigates in the arena, and he will spawn multiple Phantom Ganons to attack Link at the same time. At this point, the other sages join Link in the battle, each fighting one of the Phantom Ganons while Link battles the real Ganondorf himself. When Ganondorf reaches half of his new max health, he will dispel his Phantom Ganons and shove all the sages away, effectively stunning them. He then beckons Link to come at him, and during this effective third phase unleashes a new attack upon Link; a swarm of gloom wraths that upon making contact with Link permanently take away one of his hearts, though it will deal standard damage if Link is down to just 1 Heart Container (this damage would otherwise be fatal, but it can be withstood with 1-hit protection). When his health has been fully depleted, and nearing death, Ganondorf will instigate a Hail Mary attack and swallow his Secret Stone, effectively turning into what becomes the fourth phase of the boss battle, the deadly Demon Dragon.