It's a long time since I read them all, but when younger The Hound of the Baskervilles certainly spooked me
What do you think is the creepiest Sherlock Holmes story (poll)

The Adventure of the Engineer's Thumb. The bad guys get away and all the engineer has in exchange for Holme's interest in the case is becoming older but wiser when Holme's solves it.

I'm torn between the Creeping Man and the Devil's Foot. Both were unsettling, but in the end I think I was more freaked out by the Devil's Foot...

Actually, in reflection, both The Devil's Foot and The Five Orange Pips were scary beyond all reason to me.
What do you think it is. Only for people who have read (not watched) all of the Sherlock Holmes storys