Archive.org has scans of almost every issue of Twilight Zone, Fangoria, Famous Monsters, and Starlog, among others. The collections are not legal, yet they’ve been on Archive.org for quite a while now without ever getting removed.
Fangoria at Archive.org (347 files)
Famous Monsters of Filmland at Archive.org (221 files)
Twilight Zone magazine at Archive.org (64 files)
Starlog magazine at Archive.org (428 files)