Maxwell Rayner was the leader of the People's Church of the Divine Host during the 1980s and 1990s. However, various men called "Rayner" have associated with followers of The Dark since at least the 1700s (MAG 140). Each "Rayner" has different physical characteristics; most notably, his ethnicity changes drastically over time. Nearly all incarnations of Rayner had cloudy white eyes and appeared to be blind, but none seemed inconvenienced by this apparent blindness. It is likely that each Rayner was the same being transferring its consciousness between bodies.
Rayner was first mentioned in 1864 (MAG 98) where he is described as an old black man accompanied by a young Arabic boy. In February 2017, an old white man identified as Maxwell Rayner was killed by the police (MAG 73) in the midst of breathing a dark mist into the body of a young man named Callum Brody. It seems likely that Rayner was attempting to transfer himself into Brody's body. It is not clear whether the Rayner entity survived the death of its previous body.
The first incarnation to bear the name "Rayner" appeared in 1715 (MAG 140). John Flamsteed, the first Astronomer Royal of England, had developed a bitter rivalry with Edmond Halley; Flamsteed gave Halley the mocking nickname "Reimers" after Nicolaus Reimers, arch-rival of Tycho Brahe. One night, Flamsteed saw Halley sneak away to conduct "pagan rituals" in service of the Dark. Flamsteed confronted Halley and ultimately drowned him in a pool of Dark water, but Halley appeared again several days later, apparently alive and well. Halley thanked Flamsteed profusely for giving him "freedom," but Flamsteed could see black water and dark mist behind Halley's eyes. Jonathan Sims believes that the name "Rayner" is a corruption of the nearly-identically-pronounced "Reimers" over the centuries.
Rayner seems to have forced Robert Montauk to kill for the cult, first by kidnapping Robert's wife (Linette) and later by threatening his daughter (Julia) (MAG 9). Robert later turned on Rayner and killed his cultists, temporarily banishing the darkness monster (MAG 143). Several years later, Maxwell visited Robert in prison and tells him that the creature has returned (MAG 52).
He seems to have had an interest in John Franklin's Lost Expedition. The reason for this interest is not clear, but likely has something to do with the extended periods of darkness in extreme northern latitudes.
Rayner and his cult spearheaded the creation of the space station Daedalus in collaboration with the Lukas Family and The Fairchilds (MAG 135). All three groups had considerable material resources, but none could have financed space exploration on their own. Rayner initiated the project in order to create a "dark sun" for the Dark's ritual; he was convinced that such a thing could only be made in space. Rayner's agent successfully completed the dark sun and returned it to Earth.
There is a character named Joseph Rayner, who may or may not be related to Maxwell, who was involved with The Piper in World War 1 (MAG 7).