Not to be confused with the Krell, an extinct race of advanced beings; or with Kell, a wandering troublemaker.
Krell was a Reticulon Gray locked in battle with the Cepheids, who had decimated their number. Krell followed them to planet Earth and set out to track down and cure the Earthlings they had infected before it was too late. Intercepting an airplane flight, he discovered that one of the passengers, Kelly Taylor, had been infected; but while removing her to his ship he was hindered by her brother Morgan and was forced to kidnap him as well.