In the Anime Series continuity, Horrors (ホラー, Horā) are demon-like creatures from the Makai Realm that plagued the world and enemies of the Makai Order since immemorial times. As the anime continuity is set in many different time periods, the Inga form of Horrors look different with each series.
During the era of The Carved Seal of Flames, Horrors that plagued Valiante Kingdom were Mendoza's personal army and thralls, controlled through the use of Zirkel's Ring. Even so, independent Horrors were also present as result of the scarcity of Makai practitioners caused by Mendoza's witch hunts. Once Alfonso takes the throne, he begins a systematic extermination of numerous Horrors that continue to terrorize his kingdom, including surviving thralls of Mendoza after the mad Makai Alchemist's assumed death.
- Black Knights
- Blood Moon
- Grand Magus
- Masked Horror
- Blade-Armed Spider Horror
These are Horrors that appear in GARO: The Crimson Moon, their manifestion from the Makai into the human world having influenced the myth of the Preta. Some of them are thralls of Ashiya Dōman.
- Kamaitachi & Yamanba
- Kosode No Te
- Te No Me
- Butterfly Horror: A Horror that possesses the body of Kamo no Yasunori. This Horror is able to fly, shoot a fireball from its mouth, use the proboscis in its forehead like a blade and spread pollen that is able to consume humans. Slain by both Yasusuke and Raikou.
- Mask Horror: A Horror that possesses the body of Minamoto no Tōru. This Horror (in human form) consumes good-looking humans by kissing them, maintaining its youthful appearance. In Horror form, it is able to use countless mask projections to fire an energy beam. It could transform his arm into single blade to attack. Slain by Raikou.
- One-Eyed Horror: A Horror that possesses the body of Tachibana Masamune's unnamed wife through her anger at her husband's constant infidelity. It is able to sprout a fleshy bud that can mimic the face and;; voice of a woman in a man's heart, for example, Seimei to Raikou. Slain by Raikou.
- Dual-Bladed Horror
- Whip Horror: A Horror that possesses the body of an unnamed aristocrat. As its name suggests, it could use several whips to attack the enemy. Slain by Raikou after it manages to battle with Seimei for a short period.
- Shuten-dōji: Horrors that possess the bodies of abandoned children of the village at the foot of Mount Ooe. These Horrors consume pregnant women. Slain by Tokiwaka.
Major Horrors featured in Vanishing Line are part of King's legion, banded together to plung the world into a digital apocalypse. Also, Inga Horrors in the series depicted more insectoid in appearance and instead of traditional bat-like wings, they have insect legs-like protrusions.
These are unnamed Horrors that had brief encounters with the main characters before being slain:
- Unnamed four-handed giant Horror (Episode: Tempest): A Horror that appeared on Ema Guzmán's flashback, with three Makai Knights charging towards it.
- Unnamed arachne Horror (Episode: Burning Ashes): A Horror that fought against Alfonso San Valiante not long after Alfonso was chosen by the Garo armor.
- Unnamed Horror on wheels (Episode: Burning Ashes): A Horror that fought against Germán Luís and Alfonso San Valiante not long after Alfonso was chosen by the Garo armor.
- Unnamed Horror (Episode: Ring): A Horror Lady Viola summoned and tried to control it, but she got possessed instead. The Horror reappears once again trying to attack Sophie as she hides from Surabhi, but it is destroyed by the magic vial Sophie received from Gina earlier.