|Resided in||Halls of Colossus
|Appears in||ESO, Legends|
Kaalgrontiid is believed by some to originate from Alduin's rage in Atmora and Skyrim, having been driven to split off from the bulk of his kin in the north in order to sate his own pride and ambition. This behavior is considered normal for dragons, who are naturally driven to seek mastery.
When Elsweyr was composed of sixteen kingdoms, he and his rage of dragons came to dominate the land and above all, consume the Moon's lunar power. Kaalgrontiid in particular hoped that with the Moon's power, he would become Akatosh's equal. To stop them, The Khajiit hero Khunzar-ri recruited four companions, Nurarion the Perfect, Flinthild Demon-Hunter, Anequina Sharp-Tongue, and Cadwell the Betrayer. When fighting them proved to be futile, Cadwell suggested that it may be best to convince the dragons that they were now a willing part of their plans. In preparation, Anequina attuned to Shadow Dance Temple, incited the moons to align to form an eclipse, allowing the Moon Gate of Anequina to open a portal the Plane of Jode, where the object the dragons desired, Jode's Core, rested. The dragons' ambitions would be their undoing, as the dragons accessed the Plane of Jode, but Khunzar-ri convinced them to not simply absorb the power of the core like they originally intended, but instead store their energy within it in the guise that they would combine the lunar power with their own. The gamble worked, and the dragons were weakened enough for them to retreat back into the wilderness. To finish the job, Khunzar-ri once again convinced the dragons to play a part of his scheme. He managed to lure them into the Halls of Colossus, where he managed to seal them away. The Dragons would be obscured as "demons" in legends, and become the fabled "Demon Weapon". Their power would be coveted by many people.
After the retrieval of the fabled Wrathstone in 2E 582, the Imperial battlemage Abnur Tharn inadvertently unleashed the Dragons from their containment from the Halls of Colossus, thus allowing them to continue in their quest for the lunar power of Jode's Core. The Dragons allied themselves with the forces of Euraxia Tharn, who was led to believe that the Dragons were complacent with being used as tools. The Dragons were quick to cross Euraxia when she was no longer of use to them, and was left without their aid against the forces of Elsweyr Defense Force, which was allied with the Vestige. This turn of events resulted in her death and the return of Rimmen to Khajiiti control. With Euraxia's forces lacking a leader, they allied themselves with the Dragons in fear of their wrath. The Dragons were eventually able to force their way into the Plane of Jode where Kaalgrontiid began consuming the core's power. With the help of the Vestige, the descendant of queen Anequina, Khamira, was able to banish Kaalgrontiid from the plane before he was able to fully absorb the lunar power.
Kaalgrontiid was eventually able to regain his composure and made his way into Pellitine, finding that his underling Laatvulon had failed him. Kaalgrontiid took command of the remnants of the New Moon Cult and ordered them to do his bidding. Kaalgrontiid planned to siphon the energy he obtained from Jode's Core through a giant cluster of Aeonstone, hoping that he would become empowered. These stones would then be used to empower Dragons and collected on the island of Dragonhold. Eventually, the island's massive collection of aeonstone was utilized by Kaalgrontiid in hopes of ascending to godhood and fulfilling the New Moon prophecy. If Kaalgrontiid had succeeded, he would have fulfilled an ancient prophecy and become the Dark Aeon, also interpreted by the Khajiiti people as a new moon which "presages a time of darkness and the birth of a new supreme being."
To prevent anyone from disrupting his plans, Kaalgrontiid utilized the energy of the Aeonstone to create an aegis, a massive and impenetrable ward, around the ancient fortress of Dragonhold. and The Dark Aeon also began corrupting those near Dragonhold, turning them into crystalline beings. Through the combined efforts of Nahfahlaar, the reformed Dragonguard, and Queen Khamira's forces, Kaalgrontiid was slain and his soul was disintegrated by Nahfahlaar, and his rage of dragons were defeated. 
- Cadwell's dialogue in ESO: Elsweyr
- Loremaster's Archive - Dragons in the Second Era — Camilla Calsivius
- Kaalgrontiid's dialogue in ESO: Elsweyr
- Khunzar-ri and the Demons
- Khamira's dialogue in ESO: Elsweyr
- Events of The Halls of Colossus in ESO
- Events of Two Queens in ESO: Elsweyr
- Events of The Final Order in ESO: Elsweyr
- Events of Jode's Core in ESO: Elsweyr
- Abnur Tharn's dialogue during The Dark Aeon in ESO: Dragonhold
- Events of The Dark Aeon in ESO: Dragonhold
- Events of New Moon Rising in ESO: Dragonhold