John Bellairs Wiki
John Bellairs Wiki

From TheMillions.com:

In his lifetime, from 1938 to 1991, John Bellairs authored 15 young adult horror books. His work is distinguished by three different “series” that focused on a particular teenage boy protagonist: Lewis Barnavelt, Anthony Monday, and Johnny Dixon. In each series of books, the protagonist becomes wrapped in a mystery that involves fighting some force of evil: deceased knights, maniacal wizards, or British occultists bent on destroying the world.
John Bellairs’s most famous young adult novel was his 1973 debut, The House with a Clock in its Walls. But the Bellairs books I knew best as a child were those in the Johnny Dixon series. In them, Johnny, who lives with his grandparents in 1950s Duston Heights, Mass., because “his mother was dead and his father was flying a jet in the Air Force” (an actual description from The Secret of the Underground Room) finds himself involved in frightening adventures with his friend Professor Roderick Childermass. Professor Childermass is an active professor in his 70s who is cranky, smokes Balkan Sobranie cigarettes (one of the oldest brands of luxury tobacco in the world), an expert on the occult, and loves to bake cakes (with fondant icing) and other complicated desserts with Johnny.