The Atomic Submarine (1959)

Starring Arthur Franz, Dick Foran, Brett Halsey, Tom Conway, Paul Dubov
Directed by Spencer G. Bennet
(actor & director credits courtesy IMDB.com)

The crew of an atomic submarine are tasked with patrolling the Arctic Circle, and stopping an unknown adversary that's been destroying vessels, which they discover is not from this Earth.

One of a number of films in the 1950s produced by special effects artists Irving Block, Jack Rabin, and Louis DeWitt, this is one of their most impressive looking, despite having to combine their visuals with a large amount of stock footage.  The alien ship is effectively designed and smartly shrouded in darkness for much of the picture, and its unique occupant is appropriately striking and fearsome.  Orville Hampton's script is also well-composed, although a subplot creating conflict between Franz and Halsey is while topical a bit too familiar a trope.  The ensemble cast however is most welcome, with Franz a familiar sci-fi headliner, Foran good to see as the sub's determined commander, Conway memorable as a thoughtful scientist, and veteran screen cowboy Bob Steele enjoyable as the sub's grizzled chief petty officer.  The eerie electronic music score by Alexander Laszlo helps create a suspenseful mood throughout and combined with the visuals and the experienced cast makes this an entertaining picture on what had to have been a limited budget.