Dr Sivana pinup by ~simonpimpernel on deviantART
Without a doubt, my favorite mad scientist is the one and only Doctor Thaddeus Bodog Sivana, archnemesis of your hero and mine, Captain Marvel, and RIGHTFUL RULER OF THE UNIVERSE!!! HEH HEH HEH! He's just so willfully, deliberately, unequivocably, and joyfully eeeeeeeeeeevil! How can you not love a villain whose stated goals are as follows:
1) Become RIGHTFUL RULER OF THE UNIVERSE!!! in fact as well as in name;
2) Further the spread of evil, cruelty, and nastiness throughout the cosmos; and
3) Humiliate, discredit, and ultimately KILL CAPTAIN MARVEL!!!!! HEH HEH HEH HEH HEH!!!!!
That's in no particular order, of course.
Doctor Sivana (RROTU!!!) is like the perfect mad scientist. Disgusting little troll? Check. Lab coat? Check. Giant glasses that take up a full third of his face? Check. Bald of Evil? Check. In a comic book cosmos of increasingly gray morality, it's oddly comforting to read about a card-carrying villain who just wants to take over the world and make everyone miserable, no ifs, ands, or buts.
(Re: The hours upon hours of your life you're now going to waste surfing TV Tropes Wiki? You're welcome. HEH HEH HEH!!!)
Incidentally, I mentioned before that I thought Armin Shimmerman - Quark from Star Trek: Deep Space Nine - would make a good Sivana, and that's him in the picture above, buried under 20 pounds of Photoshop magic. That's my choice for a live-action movie; in a cartoon, no one but no one should play Sivana but Wallace "Inconceivable!" Shaun.
Can we get another shot of Sivana? Preferably by Mike Wieringo?
DR. SIVANA by *Wieringo on deviantART