The magazine that every early monster fan usually can remember as an influence on them is Warren Publishing's Famous Monsters of Filmland. If something is popular and a comic book publisher sees a market, they will try to create a magazine that is similar to the already successful model. In the 1970's the folks at Marvel Comics tried their version of a monster fan magazine, Monsters of the Movies.
The cover to the April 1975 issue is by Luis Dominguez. He was doing many covers for the DC Comics line of mystery books during this same time.