Virgil Finlay was a prolific illustrator of pulp magazines from 1935 almost until his death in 1971. The first drawing above is an original work "Venus". done in a stipple technique for which he became known. A description of his use of stipple combined with cratchboard work is at this biography at JVJ Publishing. The next two covers from Famous Science Fiction and from the Magazine of Horror show this technique.
He painted cover art later in his career. You can see more of these on Ebay. He died of cancer at the relatively young age of 56. Several republications of his work have been issued in the intervening years