The Neighbor of the Beast
(The fifth book in the Kent Montana series)
A novel by Lionel Fenn (Charles L Grant)
As Bog-Muggoth, an ancient, evil demon, arrives at 668 Langford Place, other vile gods from beyond time and space join him, and only Kent Montana can keep these creatures from feeding on the human race.
Used availability for Charles L Grant's 668
October 1992 : USA Mass Market Paperback