Actually, this should probably be listed as STRANGE WORLD OF PLANET X. Still, every print on TV or VHS and every Poster, Lobby Card and memorabilia has always listed this film as COSMIC MONSTERS (plural).
What's up? Does imdB have a source for that spelling?
The original British print is correctly titled THE STRANGE WORLD OF PLANET X (copyright 1957), and the American prints carry the singular title THE COSMIC MONSTER, but all US publicity use the plural COSMIC MONSTERS. The recent June 9 2011 TCM broadcast of the American print was missing only a two minute pub sequence from the first reel, with all violence intact, especially the incredibly gory scene of the giant insect crunching on the dead soldier's face, which was shorter on the DVD carrying the original British title.
"I take pleasure in great beauty" - James Bond