He was one of the good guys in classic horror movies...
Poking around, I found this tribute on YouTube. It sums up his story better than I can, and if you're intrigued at all, watch the video:
https://www.youtube.com/watch?v=DSjTU84Qk9M
For more, check out the links below:
https://travsd.wordpress.com/2018/04/30/david-manners-lived-up-to-his-name/
https://en.wikipedia.org/wiki/David_Manners
He led an interesting life, once married and divorced, and then lived for 30 years with his gay partner, playwright Frederic William Mercer. Mercer died in 1978, and Manners died 20 later at 98 years old.
