Real world article
(written from a production point of view)
Boris Karloff (23 November 1887 – 2 February 1969; age 81) appeared as "himself" via footage of his role as Frankenstein's monster in the film Frankenstein, which appeared in the Star Trek: Enterprise second season episode "Stigma".
During his career he hosted Thriller (1960-1962), a television anthology series that originally told ordinary tales of crime and mystery, but later became a showcase for Gothic horror stories. Many Star Trek actors made appearances on this program in their early careers, as well as appearing in some of his films.