Steranko painted the covers for this Shadow paperback series that ran for 23 volumes between 1974 and 1978.

From the back cover:

WHO KNOWS WHAT EVIL LURKS IN THE HEARTS OF MEN?

Great are the wonders of modern science and terrible their powers of evil when they fall into the wrong hands. And here could be no worse hands than those of Professor Folcroft Urlich, the brilliant and utterly unscrupulous man of science from whose hellish laboratory issued the horrible 'silent death"--murder so ingenious, so undetectable, that its victims appeared to have died of natural causes alone.

Who knew where the plague of death might strike next? Who could match wits with this most prodigious of criminal masterminds! Who might rid the world of the ghoulish terror that dogged its footsteps! The answer to all these questions was only an eerie laugh--the sardonic sound of quiet triumph that emanated from a ghostly figure garbed all in black, whose sparkling eyes and gleaming automatics sent a chill of fear through the hearts of wrongdoers everywhere...The Shadow!

Originally published in THE SHADOW Magazine, Volume 5, Number 3, April 1, 1933.