Not the horror magazine, this is an earlier American title that ran from 1919 to 1923. Shadowland covered the arts in general with a preference for stage and film. The thing that immediately sets it apart from other film magazines of the period is the cover art by AM Hopfmuller; many of the paintings resemble theatre backdrops or backgrounds for animated films. The Internet Archive doesn’t have a complete run, unfortunately—the examples here are from volumes 1, 7 and 8—but more of Hopfmuller’s work may be found on other sites. The magazine interiors are also worth a browse for their colour plates and art photographs. (Thanks to Kristian for the tip!)
These are wonderful!