That the Christopher Pike character from The Original Series was played by Jeffrey Hunter
His portrayal in this role appeared in the first episode to be filmed in the 1965 pilot episode of the series. This episode was rejected at first and a new first episode was reshot and recast with William Shatner.
The Christopher Pike character was reimagined by reusing the footage of the original pilot episode in the later episodes of 'The Menagerie' in 1966. The Christopher Pike character in the beep chair from these episodes was played by a different actor.
In later years, the Christopher Pike character was often referenced in later movies and as a main character in the modern series 'Discovery' and 'Strange New Worlds' where he is played by Anson Mount.
The original actor Jeffrey Hunter would never live to see any of this fame or notoriety of his original character because he tragically died in 1969 from a movie stunt accident when he was 42 years of age, four years after he had appeared as the original Christopher Pike. He never lived to see the fame and popularity of the Star Trek franchise or the character that he had originally played.
It's one of the saddest things I ever discovered about the actors and people that were part of the whole Star Trek franchise.