Jack Ward; Ellen Ward; unnamed cousin of Ellen Ward and his gang
Ellen Ward's cousin concocts an elaborate scheme posing as aliens in an attempt to claim her inheritance from a deceased uncle, but Jack Ward figures out the hoax and captures Ellen's cousin and his gang.
Mike Hunter; Eddie Hunter; employees of Hunter Brothers Construction; Emile LaTour (as monster); employees of Emile LaTour (as monsters); French government official and police
Mike and Eddie Hunter's construction company is hired to bore a road tunnel through Giant's Tooth, a mountain in the French Alps. As they complete the tunnel they are attacked by beasts, who turn out to be Emile LaTour's tunnel crew from a century before. The beasts save the Hunters' crew from being transformed into beasts and are retrapped in a tunnel cave-in.