Maxwell Rayner was the leader of the People's Church of the Divine Host during the 1980s and 1990s.
Maxwell was first mentioned in 1864 (MAG 98) where he is described as an old, blind, black man accompanied by a young Arabic boy. Later, another man identified as Maxwell Rayner is killed by the police (MAG 73) when he was trying to transfer his power into a young Callum Brody. It seems likely that Maxwell is able to transfer his powers (and possibly consciousness) between bodies. If this is the case, it is likely he is an Arabic man from the late 1800s to mid 1900s, is black from the early 1800s to late 1800s and white after the mid 1900s.
He seems to have assisted Robert Montauk in identifying victims of his ritual which lead to Robert banishing or killing the creature that took his wife (MAG 9). 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, although it is not clear why.
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).