"The Eliminator"
When Clark Kent calls Superman to his aid when a dead man comes back to life, the deceased man curses Clark Kent's close associates to imminent death. Clark scoffs and passes it off as bad joke, until several of his fellow reporters die in strange succession.
"Tales of the Legion of Super-Heroes, One of Us is an Imposter"
When the Legion computer reports that one of the existing members at a meeting is an imposter, it sets member against member.