I have a feeling JACK pigeonholed himself to crazy roles.
Black Queens? gotta search the torrents for that.Well who knows what the guy is like in real life. I just, while watching the clip you posted, had a thought that maybe if he had never taken the crazy patient role he might not have become the dark character that we know and love.
BTW wikipedia lists his film debut as a low budget movie called Black Queens which is not linked correctly.
Posting the date of that clip made me check. It was the sequel to "Mister Roberts" that Jack was in, "Ensign Pulver". (1964)OH, then you will LOVE the B&W 1960 version of Little Shop Of Horrors.
Roger Corman's Little Shop of Horrors "Jack Nicholson at the Dentist" - YouTube
I had heard it was his first screen appearance. I must find and watch Mister Roberts again to disprove that