Guardian Spirits, also addressed as Spirit Guardians on a few occasions, are glowing white creatures with a very strong connection to light, who are the biological children of the Spirit Tree. Ori, the main protagonist of Ori and the Blind Forest, is a Guardian Spirit.
Guardian Spirits come in many different shapes in sizes, ranging from short and stout to tall and lanky. One feature that they all share is their color, spiritual white. They also all glow with their father's light.
Most of their kind also have ears and tails, which can be long or short.
Many Guardian Spirits appear to have had unique talents, indicative of their Ancestral Trees. Some of them were small and lithe and danced through the air, while others were strong and courageous, letting nothing stand in their way. By absorbing the light of fallen Guardian Spirits, one could claim these special abilities and traits for their own.
Being creatures of light, Guardian Spirits require the Spirit Tree's power to survive.
The first appearance of the Guardian Spirits (besides Ori, whose tale begins at the same time as the narrative itself) is in a cutscene recounting the fateful Light Ceremony, where Kuro ambushed the Spirit Tree and the many Guardian Spirits who attended the gathering. Sein explains that Ori's kin were attacked, wounded, and even killed by the dark owl's misguided will; this resulted in an abundance of Ancestral Trees, the arborescent monuments marking each of the Guardian Spirits' final resting places.
With the addition of the Definitive Edition, two named Guardian Spirits are given cameos: Eki and Sol. Appearing as spiritual wisps of Naru's past, she and the pair form a temporary friendship, despite Naru being lightless. They played catch with a ball of shining light the day Naru's Father separated them permanently.
After the death of Naru's Father, Eki attempted to find Naru, but failed and turned into an Ancestral Tree in the Black Root Burrows. Sol, too, eventually became one herself in the Lost Grove.
The final appearance of other Guardian Spirits is at the end of Ori and the Blind Forest, after the fires of Mount Horu were quenched and light was restored to Nibel. From bright falling leaves of the Spirit Tree's branches, young Guardian Spirits are 'born' upon the freshly regrown foliage.
- Ori, Fil, Eki, and Sol are the only named Guardian Spirits who appear in their Guardian Spirit form, not just their Ancestral Tree form.
- Guardian Spirits might have originated from other places than the Forest of Nibel, as Eki and Sol were already alive by the time the Spirit Tree was just a sprout.