It is likely that Mamoru/Tuxedo Mask from Sailor Moon will become one of these in Crystal Tokyo. Though it seems he will use his power for good.
Charles zi Britanniamay have some elements of this. At least, by the standards of science set in the show, since he seemed to have spent a great deal of time working on the Sword of Akasha, and had a near-complete understanding of the Applied Phlebotinum found in the show. His (technically older) brother V.V. is a much straighter example. He's the head of the Geass directorate which studies geass and would have been emperor if he hadn't received a Code when he was a kid. Since we know so little of their pasts, however, the extent to which they're understanding of the show's technology and Applied Phlebotinum allowed them to come to power in the first place is up for debate. Advanced Knightmare Frames and a desire to get ahold of the precursors' Lost Technologydefinitely played a big role in their conquest of over one third of the world, however.
Subverted in the original Buck Rogers comics. It turns out the Yellow Peril villain he'd been fighting was actually a nice guy who'd just got caught up in his scientific pursuits & left the running of his kingdom to corrupt advisors.
In one issue of Superman, a potential future is shown where Lex Luthor continually lives on through cloned bodies of himself and embarks on an endless war of conquest of the galaxy/universe.
The High Evolutionary in the Marvel Universe created a race by forced evolution of animals and called them New Men. Then he created an entire planet, Counter-Earth, where they could live. Then he evolved himself into a godlike being and outgrew this trope.
In the first Micronauts comic series, the main villain, Baron Karza, was originally Chief Scientist of a benevolently ruled Microverse. He slaughtered the ruling family (except for Princess Mari) and ruled with an iron fist for a thousand years.
A Spark of Genius: A Buffy the Vampire Slayer, DC Universe and Girl Genius crossover has Xander, thats right Xander become the ruler of Romania which he rapidly turns it into the leading scientific nation which all began with the infamous 'Halloween episode' turning him into the son of Agatha Heteordyne and Gilgamesh Wulfenbach, son of the man in the picture above.
Ming the Merciless was more or less portrayed as such in the old Flash Gordon movie serials.
Another Yellow Peril example: Sax Rohmer's Dr. Fu Manchu, who aspired to become literal Emperor of the World by eliminating the white race..
Then there's a rare female example from Sax Rohmer's The Million Eyes Of Sumuru. The scientifically-savvy title character wants to eliminate love and control an Empire where women are in charge.
The Big Bad from the second Heroic Trio film fit this trope as a mad scientist taking over Hong Kong using his scientific intellect.
This is the goal of the King in Anna in the Court of the King of Siam. Given the annoyingly long title, you can understand why they abbreviated it to The King And I in the musical.
Leto Atreides II from the Dune novels has actually become the God-Emperor of the Universe to carry on with a gigantic genetic breeding experiment.
Before him, Dr. Kynes became leader of the Fremen because of his attempts to terraform the planet.
The cymektitans, philosopher kings and scientists, particularly ones that dealt with robotics, cybernetics, and artificial intelligence.
Though not canon, the prequels state that one former Padishah Emperor, working under a false name, was an accomplished chemist that discovered the properties that made Spice so important. The original books state it was a chemist working for that emperor, so it all depends what you want to believe.
Muad'dib himself was known as the Mentat Emperor. Considering he was the prophesied Kwisatz Haderach, this isn't surprising. Subverted in that ultimate trajectory of events was beyond even his control, and he knew it.
Mercedes Lackey's Mage Wars trilogy has both types: the evil Ma'ar, creator of the makaar, and the benevolent Urtho, creator of the gryphons (who regard him as an almost godlike being who created them as an improvement over all other sentients)
The Eternal Emperor of the Sten series. A brilliant engineer, his twin discoveries of the super-efficient power source Anti-Matter Two and the means of obtaining immortality allowed him to become ruler of the known Universe for thousands of years.
In Hannu Rajaniemi's The Quantum Thief the seven Sobornost Founders are implied to have been the first group of scientists who figured out human mind uploading and quantum entanglement, and realized that this puts them above any corporation or government on Earth in terms of power if they keep it for themselves. By the time of the book is set in they rule most of the inner Solar System.
Justinian in Belisarius Series is a subversion. He is a scientist and he is an Emperor, but he became emperor by ordinary means of political scheming and his scientific side was just a hobby until the war with the Malwa made him put his mind to new military technology.
Live Action TV
Davros from Doctor Who definitely meets ALL the definitions of this trope.
When his Daleks haven't turned against him, anyway. They usually do that on Thursdays.
Rassilon, who basically made the people of Gallifrey into the Time Lords. An impressive scientist even by immortal standards, he found time to invent a bewildering number of absurdly advanced technological artifacts. Also had a bit of an ego and may have been into kidnapping beings from across space and time to fight in games for his amusement. Subsequent indolence in Time Lord society may have been a deliberate effort to curb the potential of individual members of their race from also becoming Emperor Scientist types.
In the Expanded Universe Rassilon comes across as a more villainous figure, with it being heavily implied he was behind the accident that left his friend Omega trapped in a black hole. In Big Finish Doctor Who he is a massive Evilutionary Biologist, stealing the power of regeneration from the peaceful Vampires and preventing any race evolving that could threaten the Time Lords by imprisoning them in another Universe.
The Rani set herself up as the ruler of an entire planet just so she'd have an endless supply of test subjects.
The Master, who is of the same race as Rassilon and the Rani, took over the Earth by using mind-altering satellites to will the British populace into making him Prime Minister. He was also responsible for the massive Airborne Aircraft Carrier over the Atlantic as his base of operations, and created a paradox machine that allowed humans from the far future to conquer their ancestors in the 21st century.
Kate Stewart could arguably be considered a benevolent version of this as head of UNIT, where she has reformed the organisation from a simple military operation into a Badass Army that combats alien threats to Earth with science, in addition to using her father's tried and true method of Five Rounds Rapid.
In "Robot", Helena Winters is trying to become one of these. She's a blue-sky researcher who wants to reform the world based on scientific principles, which means Putting on the Reich, murdering people with a robot and trying to start a nuclear war.
In Stargate Atlantis, the commanders and scientists of the Wraith are usually the same people (always at least the same caste); most prominently, recurring Big Bad Michael and recurring Lovable Traitor Todd, both of whom had great skill in genetic manipulation. (The Wraith are normally ruled by a Queen, but the Queen of Todd's Hive died and Michael created his own armies from scratch.)
Todd also has extensive knowledge of nanite programming, which is amazing considering the last time they had to do that was 10,000 years ago. Then again, the Wraith have a Hive Mind of sorts that allows one to tap into the collective psychic network. It's possible that this knowledge rests there.
Walternate in Fringe is on the way there. He is the US Secretary of Defense and appears to have nigh-unlimited authority. While his goal is not world domination, it is world destruction, just not his world. He's also just as brilliant as Walter.
Annorax in the "Year of Hell" two-parter. Somewhat of an inversion, as Annorax is not interested in conquest but merely re-writing reality to bring back his dead civilization (and wife). His myopic vision blinds him to the consequences of his action, causing a downward spiral where he's nuking entire planets left and right. He also commands his own nomadic battle cruiser and has a fanatical crew, similar to Nero from the Trek reboot movie.
The trope is Played for Laughs with Dr Chaotica in the Captain Proton holodeck program.
In Jonathan Coulton's "The Future Soon," the narrator becomes this when his warrior robot race takes over the world.
While he may also be lots of other things (Dark Messiah, Crystal Dragon Jesus, etc), it is made clear in no uncertain terms that The Emperor from Warhammer 40K was, during his lifetime on Terra, first and foremost a scientist who spent his time laboring away in the vaults beneath the planet building space marine genetics, creating his "children", etc, and that this was the source of his great power. Seriously. Read those Horus Heresy art books.
Well, that, and the fact that he was also one of the most powerful psykers in the universe probably didn't make him any weaker.
Technically, the Fabricator-General of Mars also counts as this since he rules the Adeptus Mechanicus, which is pretty much a self-contained, semicutonomous political entity within the Imperium and is only part of it by treaty. They are mostly left to self-govern by the other branches of Imperial government, even the Inquisition, since without the Mechanicus everyone else in the Imperium would quickly lose any ability to maintain a technological society.
Had he not been betrayed and put into a coma by Horus, the Emperor would have revealed his greatest discovery - a way to access the Eldar Webway to rapidly move from world to world without the use of the dangerous Warp dimension.
In Exalted this is the typical role of Twilight Caste Solars, especially during the First Age.
In the Magic: The Gathering universe, Yawgmoth was a sadistic biologist who believed in reaching immortality through cybernetic implants. His people eventually caught on to his plots and sent him through a portal to the plane of Phyrexia. Over the centuries, Yawgmoth morphed Phyrexia into his own ideal of paradise and became its Dimension Lord. He did later try to take over his birth plane, Dominaria, but failed.
Before becoming a Planeswalker, Urza married the Princess Kayla bin Kroog and was appointed Lord High Artificer of the kingdom, eventually restructuring the military to revolve around war machines, then later appointed Protector of the Realm over Argive and Korlis after the Fallaji conquered Kroog. Meanwhile, his brother Mishra used his mechanical expertise (and his Weakstone artifact) to usurp control of the Fallaji tribe that had enslaved him, and then unite all the tribes into a kingdom.
The Great Beings of BIONICLE, though they tired of the day to day workings of ruling Spherus Magna and made the Element Lords to do that part of the job for them. It didn't workoutwell.
Regent Cid from Final Fantasy IX is the regent of Lindblum, one of the biggest and most powerful kingdoms in the game. He also possesses a brilliant mind for engineering, being heavily involved in the creation of groundbreaking new airship technology, despite the fact that he has been transformed into an oglop (small, annoying creatures, similar to vermin) and later a frog And this transformation isn't because of an evil curse or experiment gone wrong. It's because his wife caught him with another woman.
On the darker side of this trope, there's Garland: the de facto ruler of all Terra, he's also a powerful mage and an innovative scientist; by the time you meet him, he's successfully created an entire species of soulless drones and planted an organic siphon-refinery on Gaia to slowly vaccuum Gaia's soul-cycle away. And then there's his greatest creations, his Angels of Death. Kuja and Zidane.
Emperor Solomon Petresun from the Tribes video game series was originally a scientist who invented Cybrids, fought them into nigh extinction when they Turned Against Their Masters, made himself immortal for that purpose, and eventually took over the Earth to protect it from the Cybrid's imminent revenge.
It should be noted that the above example is a retcon that first appeared in the manual to Starsiege; none of the previous games (Earthsiege, it's expansion or sequel, or Missionforce Cyberstorm) mentioned the Emperor at all.
The Pig King in Mother 3 has aspects of an Emperor Scientist despite not being a scientist at all, and just stealing all of his technology from the aliens in the previous game and/or having Dr. Andonuts do the work for him.
The Shapers in Geneforge are an entire sect of this type, using their ability to create hordes of genetically engineered monsters to conquer the known world.
"He may be a vampire, sadist, and mass murderer but he's also quite the scientist by the look of things." - Scree
In Sid Meier’s Alpha Centauri, this is essentially what Prokhor Zakharov, Aki Zeta-Five, and Shen-Ji Yang become if their factions win, if their personalities throughout the game are any indication. Probably Deidre Skye and possibly Pravin Lal, too.
Let's face it, every faction leader is this trope, flavored by their own factional ideology. Even Miriam relies on advanced weaponry wherever she can develop it.
The Cybran Nation in Supreme Commander is apparently ruled by Gustav Brackman (now a Brain in a Jar ), inventor of the symbiotic AI technology that defines his people. He's the least imperial of the setting's rulers, though.
Andrew Ryan from BioShock, the "greatest electrical engineer of our generation" and "the bloody king of Rapture"
High Tinker Gelbin Mekkatorque of World of Warcraft. It counts because gnomes choose their supreme leader based on his intelligence and technological skill. Also, he will kick your ass.
Ansem of Kingdom Hearts. Both of them. Ansem the Wise is a non-evil version (though he did become somewhatbitter after being deposed), while Xehanort is most certainly an evil version.
Robert House of Fallout: New Vegas, autocratic ruler of New Vegas, Insufferable Genius, and a a bit of a chessmaster as well. Prior to the war, he was one of the world's richest men, with his fortune entirely self-made through his inventions. He's also the main reason why the city and the surrounding areas survived the war relatively intact, as he anticipated the exact day of the impending nuclear apocalypse and spent over a decade of his life on planning for the event and its aftermath.
The Think Tank of the Big Mountain facility from the Old World Blues DLC are this, being a collection of mad scientists who survived the Great War by preserving their brains in jars. Most of the Mojave's resident Goddamn Bats are the result of their experiments, having escaped the facility.
The Courier, if played with High Intelligence and maxed out skill in Science, especially in the Wild Card Ending and at the end of Old World Blues. Bad Karma Couriers play this straight, while Good Karma Couriers are a mixture between a more benevolent version of this and a Science Hero.
Andross from the Star Fox games would certainly qualify, even though the method that he used to land himself into power was more comparable to Exile due to ruining Corneria.
Dr. Edward Bilstein of Star Gladiator definitely qualifies for this. Once the top physicist for the Earth Fedearation who was responsible for the discovery of Plasma Power, Bilstein was later arrested and exiled from Earth after it was discovered that he was experiminenting on various human bodies in order to further his Plasma Power research. Breaking out of prison while placing himself into a cyborg body and gathering a cadre of fighters and forces, Bilstein had soon declared himself the emperor of his organization, known as The Fourth Empire, and that he now seeks galactic domination of the universe while continuing his Mad Scientist experiments.
Dr. Weil from Mega Man Zero may have initially been a mad scientist, but via various plans and Chessmaster moves that landed himself as ruler of Neo Arcadia, he became a full blown Emperor Scientist. However, he has more interest in making everyone suffer a fate far worse than death than actually ruling over people.
By Resident Evil 5, Albert Wesker has set his sights on this. Already a capable scientist, he decided to exterminate most of mankind, sparing only genetically superior individuals with himself as their ruler.
Kastore and three companions in Might and Magic VII play a small version of this in that game (leveraging their superior scientific knowledge into becoming advisors to King Archibald, then leveraging that position to usurping the throne of Deyja), and had plans of becoming a full-scale version. Canonically, their plan failed and they never showed up again, but they were originally going to pull off the initial phase and become enough of a threat through Ancient-level science that the good guys has to resort to a magical doomsday weapon to stop them. Their 'Forge' town caused a massive Internet Backdraft, however, so that plan was abandoned.
Miranda's father is shown to be this as well. He has dedicated his life into creating an empire for himself, starting with creating a daughter who is essentially a clone of himself only modified to be as close to genetically perfect as possible. Miranda even admits that she's not the first daughter he created, only the first one he kept and when she didn't turn out how he'd like, he simply created yet another daughter. Miranda responded by running away with her infant sister (and identical clone) in tow.
Dr Gavin Archer is a milder version of this. He's responsible for the creation of the "Rogue VI" taking over Geth and turning against the personnel of Project Overlord, having been driven by fears of his project being shutdown to hook his autistic brother into supercomputer itself. The strange digital face and random electronic screaming seen and heard throughout the base are his brother's frantic attempts to cry for help.
Mao from Disgaea 3: Absence of Justice effectively becomes this. The Netherworld he lives in is one gigantic demon school called Evil Academy, his father is both Overlord and Dean, and he inherits these titles by the game's end. Unlike his father, however, Mao is a Mad Scientist whose idea of dealing with a defeated enemy is to drag them off to his lab for vivisection.
Most governments in the GG 'verse are ruled by Emperor Scientists; small, independent technocracies seem most common, but even most of the known royals (such as Albia of Britain and the Storm King's line) are powerful Sparks. However, there are exceptions: the more traditionally noble "Fifty Families" still exert some power, but seem to be in decline as their bloodlines peter out.
The foremost mad scientist and ruler in Europe is the image provider, Baron Klaus Wulfenbach. However, Klaus laments that the "Emperor" part of the job description leaves him with very little time for the "Scientist" bit. There is always an uppity petty noble with a new killbot somewhere, who needs smacking down.
The wizard emperor Brian Souballo, from Our Little Adventure. He implemented the process of transferring the Cosmic Lifestrand into clones grown in laboratories known as 'Training Facilities.' He has some powerful wizard lackeys who know how to use the machines but its shown that Brian or Angelo may be the only ones who truly knows how the process works.
Peter the Great did not exactly use science to get power, but he used his knowledge and understanding of mathematics, engineering and construction to create an efficent technical and scientific education system, build a modern fleet, and modernize industry. He even approved and edited foreign textbooks for publication by himself.
Rama IV of Thailand, better known to the West as King Mongkut or the king from The King and I, is actually known as "The Father of Science and Technology". He refined geography and astronomy most of all, and actually died from malaria caught in seeing a solar eclipse.