The Gentleman Ghost, a character created by Robert Kanigher who first appeared in Flash Comics 88 (Oct. 1947), was an elusive and recurring mysterioso foe of Hawkman throughout the late 1940s. Here, we see him in Flash Comics 92 (Feb. 1948),
When Hawkman received his jet-age reboot as an alien police officer from the planet Thanagar (Brave and the Bold 34, Feb.-March 1961), I suspect writer Gardner Fox, wanting to recapture some of that old magic, created a similar arch-criminal whose powers would be super-scientific rather than supernatural. In both cases, Joe Kubert did the art.
So Carl Sands, after saving alien explorer Thar Dan of the Xarapion dimension, was rewarded with a Dimensiometer, a device that transformed him into the intangible Shadow Thief. Hawkman’s mission to capture Sands was more urgent than he realized, because only comic book readers knew that overuse of the Dimensiometer would wreck human civilization by causing global climate change.