I'll bite...
1... Baron Frankenstein (Peter Cushing... He actually made Frankenstein a Mad Doctor.)
2... The Invisible Man (1933) It seems that the actors in every other "invisible man" are copying Claude Rains.
3... Dr. Kananga... Live and Let Die (1973)... Anybody that plans to lunch heroin filled rockets into a city to increase the number of addicts is a little insane... :)
4... Herbert West... I'm not actually sure if he's a doctor... :)
5... Dr. Josef Mengele ~ Gregory Peck in The Boys from Brazil (1978)... Cloning not 1 or 2 but maybe hundreds of Hitlers...
6... The psycho Doctor??? in Murder by Phone (1982)...
7... Dr. Phillip Spires, Dr. Tom Halman and Dr. Paul Vaughn for making the only guy that Chuck Norris couldnt give an ass kicking to... although Chuck Norris has the guy trapped inside a well. I was hoping for a part 2 (never will happen) and I wonder how much of an influence [Silent Rage 1982] for making Ringu... :)
8... Dr. Charles Luther... Runaway (1984) for making Heat seeking bullets and little toy robots that inject acid.
9... The Doctors in Twins (1988)... They must be crazy to get rid of Vincent Benedict because he didnt seem similar to his twin brother (sure it was a plot device but truthfully speaking both of the brothers would still be in a lab)
10... Dr. Alex Hesse... Junior (1994)... hehe talk about a mad doctor... :)