If you loved The Man Who Could Cheat Death, try The Two Faces of Dr. Jekyll
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Terence Fisher, and they both carry the body horror, dread mood tags, and they sit in Horror / Science Fiction territory. If that's the register that drew you to The Man Who Could Cheat Death, the second film will land in a comparable space — through a different lens.
body horrordread
What The Two Faces of Dr. Jekyll is
London fog chokes the gas-lamps. A silver syringe gleams on the mahogany desk. Jekyll’s serum loosens his collar stud by stud until a grinning stranger slaps the mirror and steps forward. Hammer’s Technicolor split stings worse than the serum.

