Wouldn’t nuclear engineering come closest?
Any truly mad scientist would need an intimate understanding of the most powerful sources of man made energy on the planet. Not to mention the basic grounding in chemistry, physics, mech e, ee, thermo, etc that nukes get.
If you can’t whip up something that’ll take out a major city and fit in the bed of a pickup truck, you ain’t no mad scientist.
Engineering alone seems like enough to be a good supervillain. Dr. Doom was the best supervillain anyway.
Math and physics are integral to engineering though. Chemistry and biology, I don’t know how important they are for being a polymath.
However to be a good supervillain you also need a good grasp of the social sciences so you can control and manipulate people into doing your bidding either intentionally or unintentionally. A supervillain needs political power, henchmen, elaborate schemes, etc.
Again, this assumes that all Mad Scientists are evil. This simply is not true.
Although he was in the end defeated by the Technocracy, Buckminster Fuller left a lasting legacy-none of it capable of blowing up a city.
AAAACK! SOlid Proof Ultra-libs are mad scientists!
But wait, ultra-libs have nice hair…
All this raises some interesting points about whether it’s possible to be a Mad Scientist who isn’t evil.
I’m inclined to say it is (Doc Brown and Professor Farnsworth spring to mind), but generally I’d say the best you’re likely to get is “Recklessly Indifferent”. I guess that’s sort of the “Chaotic Good” of the Science! world. 
Even if a Mad Scientist thinks he’s Good, or believes he’s working for the betterment of Mankind, he’s still creating Death Rays and Slave Beams.
Why? Because he’s Mad, of course. No matter what he thinks he’s doing, he’s really doing evil, or preparing to do evil if not enough people appreciate his good deeds.
Doc Brown is from Back to the Future, right? If so, he wanted time travel just so he could prove he could do it, he gives no explanation. And despite his warnings to Marty, he recklessly sends a teenager back in time who can then alter their history causing God-Knows-What.
Some irresponsisbility is evil, no matter how friendly and nice Doc Brown seems.
Plus he has crazy mad scientist hair, which proves he’s evil.
Incidentally, the name is Hair Gel for Mad Scientists™ not just Mad Scientist Hair Gel.
Romco spent a great deal of marketing money to come up with that name.
Don’t make [del]my[/del] Romco’s lawyers send you a cease and desist letter.
Ok, Ok, I’m not trying to get a bunch of [del]your[/del] Romco’s lawyers after me. I’m not even selling and didn’t concern myself with getting the name straight.
Hmmm…actually maybe [del]you[/del] Romco should send me a check for promoting [del]your[/del] their product…Hmmmm…
I could always promote Acme’s Styling Mousse for World Dominants™ I suppose. How are sales lately? I understand it’s an extremely limited niche market.
PM me on where to send the check please.
Your idle threats have been noted for the record and you may expect a visit from [del]my[/del] Romco’s corporate enforcers soon.
So, David42 (if that is even your real name), you think you have what it takes to play in the extremely brutal arena of Mad Scientist Cosmetics? I think not.
Mad? Just because your puny intellect can’t comprehend my work, you call me mad? Fools. I’ll destroy you all.
I’m not too worried. I will just recruit some lackeys to keep them at bay.
Somehow I am beginning to think that Mad Scientists themselves are behind your product. It’s probably a trick to get the public to go along with their schemes by promoting a false idea that Mad Scientists now have NICE hair, and therefore the ones with crazy Mad scientist hair are of no concern. Their plans for world dominion are simply hypotheticals.
I have thought this over and decided this thread, for a great debate, is missing a good deal of factual information that is usually present in a great debates thread. Not that I wanna shout cite! to everything anyone has said, impermissably pestering them for things we all-know-are-true, but I have determined that this is the most crucial piece of information lacking in the thread, so I will just pester you for something none of us know is true.
As a Mad Scientist, I am sure that you are familiar with citations. They look like this:
Or rather a link to a citation.
I am afraid I am going to have to ask for a citation on not only all readings you have made on the Gygaxometer of yourself for the last year but all calibration information for the past year as well. I will find the industry calibration standards myself, thank you.
Yes, I am handwaving materials from the Mad Scientists Are Good! Really! website.
Yeeeesssss maassssster i will obey
My Gygaxometer came with samples of Good, Evil, Law, Chaos, and two more that an UnActualized mind can no more comprehend than it can think in four spatial dimensions.
Frankly, I don’t use my Gygaxometer much. We on the good side of the conflict make ourselves known so that the Grey Faces can’t trick us into fighting each other. The Men in Black generally do not try to deceive you. They just try to kill you.
What was I thinking? Mad scientists don’t cite. They just say “Fools! I’ll show them all!”
Man I had a weird dream, like I was doing someone’s bidding…something about fetching lots of blinkenlights and nearly getting arrested at the Romco warehouse…and haunting images of crazy hairdos and maniacal laughter…
The hell you say!
I wrote plenty of well-cited papers including Masters and Doctoral theses. I occasionally write well-cited articles for Paradigma and other Scientific journals.
Or, if you take my approach, you declare your work to be trailblazing original research that transcendes such mundane concerns as “references” or “peer review”. 
Mad Scientist Cosmetics? And you joke? You have no idea of the evils that could be perpetrated! Ever heard of Fotoshop by Adobé?
After carefully reviewing all major journals and especially Paradigma, I can’t find any articles written by DocCathode. However, I did find an interesting piece in the Magazine “Mad Scientist Watch” with the headline: "DocCathode not Jewish, claims of innocence in Nazi Zombie attacks found to…
Yeeeeessssss Maaaaassssster I will Obey…