Heroic Spirit

Heroes who achieved great things in life, and became objects of worship after death.
As a “power that protects humanity,” they are high ranking existences, categorically closer to elementals than wraiths.
However, whereas elementals are “power” given form using the container called human imagination, Heroic Spirits are woven from people’s ideals on the inside, too.
Among the Heroic Spirits, there are those from legends, those that really existed, and those that were never observed at all. The ones who aren’t worshipped much fall under the broad classification of “Counter Guardian,” and are used as a mindless “Counter Force.”
Of all the Heroic Spirits that appeared in the story, the only one functioning as a “Counter Guardian” was Archer.
Because the other Heroic Spirits had high divinity, and were existences closer to the planet than humanity, they were able to avoid being drafted as Counter Guardians.

Fate/side material: Fate Encyclopedia