There are two famous horror studios: Universal and Hammer. I initially wrote "great", but then had second thoughts and changed it. I wouldn't want to go making claims of greatness for Hammer in general, but they're certainly a landmark in genre history. Both studios' backbones were built around two properties: Dracula and Frankenstein. In the former case the actors in question were Lugosi and Lee, while in the latter case we had Karloff and Cushing. (Hmmm. K-K and L-L. Is there an M-M somewhere?)
There's a big difference between the two, though. A Dracula movie is a Dracula movie. You can do some pretty horrible things to him, as those studios demonstrated with Abbott & Costello, Dracula A.D. 1972 and The Legend of the 7 Golden Vampires, but the core concept will remain the same. He's a vampire. He doesn't drink... wine. Bram Stoker's original is an unashamed horror novel that stands up pretty well even in painstakingly faithful adaptations.
Mary Shelley's Frankenstein however is a slow, talky exploration of ethics likely to disappoint modern readers looking for a thrilling read. The version we know owes more to the 19th century's self-devouring cycle of stage adaptations, which recreated Shelley's work of speculative fiction along the lines of the penny dreadfuls. Universal's 1931 film was based both on Shelley's novel and a stage play by one Peggy Webling. This was a runaway success and at its heart was Boris Karloff as the monster, who completely overshadowed Colin Clive's "Dr Henry Frankenstein" and became an instant star. Even today, Karloff's portrayal remains the definitive version.
Understandably protective of their property, 26 years later Universal threatened Hammer with lawsuits to stop them lifting anything from those 1930s versions. Hammer had been planning to do it in black-and-white with Boris Karloff as the Baron! Instead the script had to be rewritten to satisfy the lawyers, the make-up had to be unrecognisable and the production became the first colour Frankenstein movie. More importantly, the story's whole thrust changed. Instead of being a tale of a monster, it became a tale of a man. Christopher Lee's Creature isn't even memorable. No, it's Peter Cushing's Baron Frankenstein who's the terrifying star of the show and the one who kept coming back for repeat appearances.
In an odd way, the result is one of the most horrifying horror movies I've ever seen. It doesn't evoke fear, as such. Christopher Lee mimes his socks off as the Creature, but the film doesn't give him much room to shine. Instead it's all about Cushing, aka. my favourite movie actor of all time. Theoretically I think it's a storytelling mistake for Frankenstein movies to focus on the Baron instead of his creation. The monster is powerful in every way, capable of carrying out any action and evoking any desired emotion in the audience, while its creator is by definition a twat fixated on doing something very very stupid. It's like watching a slow-motion car crash, rubbed in over 90 agonising minutes... but truly, Peter Cushing was a god among men. (Basil Rathbone was also good in 1939, though.)
The character he creates is interesting in being villainous but neither mad nor evil. Even at his most appalling, in the aptly named film Frankenstein Must Be Destroyed, he's still driven by the furtherment of science. It's just that he's uniquely fixated on his goal, at the expense of his ethics and/or the lives and emotional stability of the people around him. For him, murder is just a way of laying his hands on raw materials. That's just what's in the script, though. What Peter Cushing brought to the table was to invest this utter bastard with old-fashioned manners and ice-cold hypnotic charm. In real life he was the kindest, most considerate man who ever lived, which you can see in his performance even when he's cheerfully murdering his way through half the cast. To be honest, I don't think Cushing had much range. When he tried to stretch himself as Doctor Who, he failed. However when basically playing himself, either in good or evil versions, no one's ever been able to touch him.
This film has one clever plot development, incidentally. Fairly obvious once it's been pointed out, but still not from Mary Shelley's original novel. Jimmy Sangster pens a free but respectful adaptation, even throwing in an old blind man. The 1931 Universal version may be both better and more iconic, but respect is still due to the film that gave the world Peter Cushing's Frankenstein. Damn, if only we could have seen Cushing and Karloff together...