The Citadel Guardians are the wardens of the Crystal Citadel, who numbered at least six. Their purpose is to arrest and imprison beings that commit cosmic crimes. The Citadel Guardians kept the Multiverse in order by keeping the prisoners frozen for all eternity. Should any prisoners escape, the Guardians would obliterate them with powerful white lasers that shoot from their heads. They have existed for a very long time, and, as of "Escape from the Citadel", they are presumed to be extinct.
Their bodies are composed of pink crystal and a central nervous system. This system is also seen in the pillars of the citadel. They have a humanoid appearance, and all seem to have at least one fractured arm and leg.
Citadel Guardians have the ability to manipulate the Multiverse and create voids, much like a void caster, to find criminals. They can immobilize criminals in frozen crystal and transport them to the Citadel. The Guardians' lasers have the ability to destroy life. Their blood has special regenerative properties that include prevention of aging and healing wounds; however, the Guardians' blood cannot restore the loss of a bone. The Guardians' blood was powerful enough to completely regenerate the Lich's body. Their abilities are easily overpowered by the Lich, whose plague wipes them all out.