The Addos were invisible beings of pure creative energy from the planet Proscenia, who used light to build their civilisation. They were linked by a mental bond to the Logos and could only build something if the Logos were there to appreciate it.
A group of Addos crashed their ship near the Bishop's Palace in 1902. There, they glimpsed a Mummers play before going into emergency hibernation. Awaking in 2014, the Addos tried to gain the appreciation of the audience by turning people into animal-hybrids, aiming to recreate the Mummers play. (PROSE: Behind You)