* Gary Cooper as Lieutenant Peter Ford
* Fredric March as Dr. Julian Osborne
* Dorothy Malone as Marie Osborne
* Anthony Quinn as Pablo
* Edward Arnold as General William F. "Willie" Garrison
* Raymond Burr as Captain Ernest "Ernie" Blake
* Peter Graves as Lieutenant Charles "Chuck" "Dutch" Van der Zee
* Earl Holliman as Corporal Jackson
* Walter Sande as Sergeant "Sarge" O'Meara
* William Hopper as Lieutenant Commander Paul "Pappy" Peterson
* Richard Anderson as Lieutenant Commander William "Bill" Parker
It's worth noting that this film was released in the United States as "A Man on the Beach" but in the United Kingdom it was released as "The Enemy Below".