At the Institute they said I was mad! But I'll show them! I'll show them all! BWA HA HA HA!!!

Has a mad scientist ever actually said this in book, film, or comic rag? What’s the origin of this stereotypical bit of dialogue?

In the Woody Allen movie Everything You Always Wanted to Know about Sex * But Were Afraid to Ask, the character of Dr. Bernardo (played by John Carradine) says things that are very close to that. He says something like “Mad? Mad? Yes, that’s what they called me at the Masters and Johnson clinic.” Of course, this particular sketch is intended as a parody of old movies, so all it shows was that when it came out (in 1972), it was already a cliche to have mad scientists talking like that, so it’s not a direct example of an old movie in which someone says that in a non-parodying way.

Bela Lugosi expresses sentiments along this line in Bride of the Monster. An old comrade from the mother country tries to get Bela to return and Bela goes on about how they all laughed at him and he’ll show them all when he creates his “Race of Atomic Supermen” and takes over the world!

Worth quoting in it’s entirety:

Without re-watching it, I think Colin Clive’s “Henry (?) Frankenstein” in the Karloff version has similar lines.