(New York World’s Fair Comics 002, 1940)
Dr Vreekill had a steel-melting ray and a dream (engage in the surprisingly common crime activity of extorting the attractions of the New York World’s Fair as a prelude to world domination) until Batman and Robin stuck their big noses into his business.
(Whiz Comics 009, 1940)
Dr Durgan, a respected scientist, develops shrinking tech and of course uses it to force tiny men to steal for him on pain of remaining tiny. All is well until he makes the common mistake of messing with Billy “Captain Marvel” Batson, boy reporter.
(Whiz Comics 009, 1940)
Dr Durgan, a respected scientist, develops shrinking tech and of course uses it to force tiny men to steal for him on pain of remaining tiny. All is well until he makes the common mistake of messing with Billy “Captain Marvel” Batson, boy reporter.
(Whiz Comics 005, 1940)
Dr Lake has a hypnotism machine which he uses to found a nation-wide network of child thieves. He doesn’t reckon, though, with the fact that Captain Marvel is secretly a child.
(Whiz Comics 002, 1940)
Kind of a generic evil scientist type – he invents a ray that can restore the dead to life but must kill folk in order to test it – but his name is James Kirk, so that’s fun!
(More Fun 044, 1939)
Not much to this fellow, just a scientist who turns himself invisible and immediately starts criming it up. He is our first invisible guy though, and he’s yet another collar by the Radio Squad. Well, almost – he hurls himself out a window rather than go to jail.
(Action v1 019, 1939)
Classic mad scientist stuff here: work out a revolutionary technique to transplant human brains into gorillas and then aim no higher than sending your gorilla-men out on horseback to plunder Mexico. Blows himself up, as per the above image.
(Action v1 015, 1939)
Just a regular sort of science villain with a regular sort of plan: create a heat ray cannon and use it to ransom the world by melting the ice caps. Derailed and frozen solid by Zatara after a mere few flooded cities. Actually, that would be a neat way for him to come back: thawed out by global warming.
Occasionally a clear super-villain is unnamed in the course of a story and I have to go by something they are referred to in captions. The Ice Menace always feels like one of those to me but I think they actually call him that during the story? Wild.
(Action v1 008-009, 1939)
Dr Kichung menaced Tex Thomson for a couple of issues in a fairly standard scientist-who-puts-human-brains-into-apes kind of way until the local apes, sick of his malarky, killed him dead. I really liked his apes though. They had gravitas.
(Detective v1 033, 1939)
Carl here is a scientist who is obsessed with Napoleon, something that people used to be when there weren’t so many fictional characters to be consumed with – heck, he appears only a few months before the Joker begins his slow crawl to being the one a weird loner would be pictured dressing up as while he makes his Important Plans.
Since Carl was a scientist he recruited a cabal of other scientists to help him make war machines and since he was a Napoleon Head he recruited an army of dudes and together these formed the backbone of his world domination scheme until he was unexpectedly Batmanned.
The real notable thing about Carl is that he was basically the last villain that Batman fought before he stopped killing people. In fact, Batman (by my count) kills the most people in this incident: at least 14, including Carl himself!
ADDENDUM: I was wrong about the “stopped killing people” part because I had a Fan Theory about how Batman stopped killing about the same time he adopted Robin. The major flaw in this Fan Theory was that Batman and Robin kept on killing people.