I recently watched for the first time Robert Wiene's The Cabinet of Dr. Caligari, featuring Conrad Veidt as Cesare the Somnambulist. It's startlingly beautiful and extremely clever. However, in the process I also discovered that Conrad Veidt had (during the course of an incredibly prolific career) been in Different From the Others, a film that advocated tolerance of homosexuality and was against paragraph 175 of the German Criminal Code. The movie was made, amazingly in 1919 (175 was revoked entirely only in 1994).
Someone has rather kindly uploaded the whole thing to Youtube, and you can watch it here. My favourite part is probably this bit below (starting at about 6:20). I'm not sure if it's revolutionary, hilarious, or a delightful mix of both.
The "female gonads" bit never fails to grab me. The Doctor, incidentally, is Dr. Magnus Hirschfield.
The movie was banned soon after it was released, and many of the prints were destroyed during the Nazi regime. Still, I love them for trying.