"The Beast" by A.E. van Vogt

Offers the story of a flawed hero possessing almost superhuman strength. When his wife is kidnapped, war veteran Jim Pendrake embarks upon a search that takes him to a lost colony on the moon--and a secret, sinister society. Originally published in Astounding Science Fiction.

If I say too much about the plot of The Beast it will sound ridiculous. Maybe it is. Suffice it to say there are underground Nazis involved in a nefarious conspiracy, immortal polygamous cowboys, an interplanetary matter transporter, a million year old genius Neanderthal named "Big Oaf", and that most of it takes place within millennia old caverns created by an extinct alien civilization on the moon. With all of that and more van Vogt manages to harness his extravagant imagination and inimitable style to tell an amazing adventure story full of action and intrigue, and at breakneck speed. Oh, and there's a saber tooth tiger.

Seriously, what other author, then or since has so consistently and unabashedly unleashed his/her imagination to such an extent? van Vogt straps a rocket to his imagination, which either explodes after launch or takes you all the way to the moon and beyond. (GoodReads)

"Monsters" by A.E. van Vogt

van Vogt proved that each monster can be just as weird and frightening as the last. Indeed, he continues his fine "space monster" tradition in this collection, where, again, each proceeding monster is as original and well thought as the last. I was expecting some cheesy storylines as one would often find from 1940s sci-fi thrasher movies, but van Vogt surprised me when he took a mature stab at all these stories. A fine collection!

The stories are all written around 1945, with 1939 ("The Sea Thing") being the earliest and 1950 ("War of Nerves" and "Enchanted Village") being the latest. Your initial suspicions would rest on generically scary squid- or ant-based aliens with slimy skins and evil intentions. Guess again.

Monsters (1965) was later republished as The Blal (1976) with exactly the same stories in exactly the same order. The only difference is The Blal's addition of giving each monster its own classification through a "genre." For the sake of cinematic drama, I've also included the genre of each monster to give it that special B-Grade sci-fi quality.

[Space Monster] Not Only Dead Men (1942, shortstory) - 4/5 - Frog-like, benevolent race of aliens coyly renders the human whalers assistive in the hunt for the great galactic space monster hidden in earth's oceans. 28 pages

[Robot Monster] Final Command (1949, shortstory) - 3/5 - Robots assisting humans in their lives prove to be equal in humanity to the humans themselves; if only they could be aware of the fact and find the means to meet that equality. 29 pages

[Avianoid Monster] War of Nerves (1950, novelette) - 4/5 - Grosvenor of the Space Beagle is back to psychically manhandle the bully avian monsters light years away with the assistance of the ship's gear and his specialty in Nexialism. 29 pages

[Martian Monster] Enchanted Village (1950, shortstory) - 5/5 - A first person pure narrative about a man shipwrecked alone on Mars where his only possible source of shelter and sustenance is an abandoned organic alien village. 20 pages

[Mystery Monster] Concealment (1943, shortstory) - 3/5 - The Watcher senses an approaching Earth starship and attempts to suicide as his warning to Fifty Suns is shot off, but the crew capture him to find the origins of his people. 20 pages

[Oceanic Monster] The Sea Thing (1939, shortstory) - 3/5 - Island stranded shark hunters confront the supposedly island shark god, which poses as a man yet can revert to a shark at will. 39 pages

[Revivified Monster] Resurrection (1948, shortstory) - 3/5 - Character laden alien craft encounters vertebrate bipedal species who have an unknown apocalyptic past which they try to revive through resurrection, yet through ignorance, too. 23 pages

[Multimorph Monster] Vault of the Beast (1940, novelette) - 4/5 - Transdimensional xeno-morph takes the shape of various humans in order to bring a talented mathematician to Mars to unlock the prime number secured vault of a mysterious entity. 32 pages.  (Potpourri of Science Fiction) (Potpourri of Science Fiction)