Apothicon

Apothicons were a group of keepers once until they discovered the Dark Aether. They were responsible of creating element 115 and the MPD. Turning dead people into mindless zombies and other creatures. They are the main antagonist of the zombies storyline of the Call of duty zombies series because of their affect of 115.

Origin
The Apothcons were once a group of keepers, creating the summoning key and trying to balance and protect the universe. When they found the dimension of the Dark Aether, the energy corrupts them into corrupted keepers. The Dark Aether made them betrays their own species, forcing the other keepers to fight against their brethren. After the war between the two keepers, the corrupted keepers were defeated and was banished into the Dark Aether. After time in there, they were turned into tentacle like creatures, being called the Apothicons. Soon after they began creating and planting element 115 in various dimensions, including the original timeline and dimension 63.

Biography
During the Middle Ages, the Apothicons somehow escaped the Aether and invaded earth. But they were fended off by the keepers. With the help of humans bravery, they were defeated again and sealed back to their homeland. Sometime later, one Apothicon called "the Shadowman" managed to escape their realm and manage to trick the four criminals in Shadows of Evil by cursing them and release the apothicons to their world using the summoning key. But the four criminals managed to fight back with the help of keepers and sealed them into the summoning key.

In Revelations, the Shadowman managed to trick Maxis upon "fixing his world," and was released from the summoning key and released his homeland to the earth, creating havoc across some dimensions. But when the Primis was summoned by Dr. Monty to defeat them. They were successfully finally defeated by the Primis. But then Maxis sacrifices his soul in the summoning key, trapping all of the Apothicons and the Dark Aether inside the summoning key. Stating by Monty that they are gone forever.