It might just be wishful thinking, but Henry Daniell was one of those rock-solid character actors who somehow "missed" becoming a major horror star. Sort of like the love child of Karloff and Whit Bissell, he seemed tailor-made for mad scientist roles of the Zucco or Atwill stripe, as evidenced by (what is probably his most prominent genre performance in) THE FOUR SKULLS OF JONATHAN DRAKE.
What put the notion over the top for me was watching Daniell's numerous performances in the THRILLER TV series, particularly his LONDON AFTER MIDNIGHT-inspired Squire Moloch in "Well of Doom," one of the most atmospheric hours of horror TV every produced. Virtually everyone who knows and champions the reputation of "Pigeons from Hell" (and I'm one of them) goes all quizzical when "Well of Doom" is mentioned, but except for a letdown ending, the latter is just as grimly-drenched.
So, I put it to you: Henry Daniell, one of the best horror stars É who never was an actual horror star.
He died on Hallowe'en, 1963.