In Disney’s Frozen II, the water spirit Elsa encounters is called the Nokk.
The Nokk appears as a magical horse formed from water and challenges Elsa while she tries to cross the Dark Sea. Elsa must learn to work with the spirit rather than simply overpower it. After their confrontation, the Nokk becomes connected to Elsa’s journey and helps her travel across the sea.
Frozen II expands the magical world beyond Elsa’s ice powers by introducing elemental spirits associated with nature. The Nokk represents water, while Bruni represents fire and Gale represents air. Earth giants also appear in the Enchanted Forest.
The definite article is part of the commonly used name: the character is generally called “the Nokk.” It should not be confused with Bruni, the small salamander-shaped fire spirit, whose identity is established separately in the same film.