Robot Master

A scientist who specializes in building or maintaining robots. If he is a Mad Scientist, this skill will probably manifest as an ability to effortlessly manufacture Mecha Mooks in bulk. Robots don't have to be his only area of expertise (as a mad scientist, he's probably also an Omnidisciplinary Scientist), but he's a Robot Master if robot-making is far and away his most commonly displayed skill. For instance, Doctor Doom is a scientist who builds robots periodically, but fellow Fantastic Four enemy the Mad Thinker builds robots virtually every time he appears.

Just building one robot doesn't qualify you for this trope. This is for people whose resumés are more than 50% taken up with robot-building or at least robot-fixing.

Not to be confused with the Mega Man Robot Masters, though this trope does apply to their creators.

May or may-not overlap with Marionette Master.

Anime & Manga

 * Dr. Gero from Dragon Ball Z.
 * Dr. Vegapunk of One Piece. This may change later on, as he's pretty much stated to have a whole plethora of other accomplishments under his belt, but his most prominent role in the story thus far is creating a small army of Pacifistas for the World Government.
 * Jail Scaglietti from Magical Girl Lyrical Nanoha. He also builds androids.
 * Winry of Fullmetal Alchemist is constantly repairing robotic limbs and such.
 * All Incarnations of Dr. Hell from the Mazinger series are this to varying degrees.
 * Dr. Rotwang from Tiger and Bunny.

Comic Books

 * Dr. Will Magnus, creator of the Metal Men.
 * The Mad Thinker from Fantastic Four.
 * Toyman from Superman.
 * Justice League of America's Dr. T.O. Morrow.
 * Alistaire Smythe, creator of the Spider-Slayers.
 * Also minor Spidey antagonists Armada and Future Max.
 * Bolivar Trask, creator of the X-Men's robot nemeses, the Sentinels.
 * The (possible) Trope Namer from Marvel's The Transformers comic is actually an invocation of this trope: failing comic-book writer Donny Finkelberg is enlisted by the government to pose as the "Robot Master" and make threatening speeches on TV taking responsibility for the Decepticons' actions, to keep the population from panicking. Hilarity Ensues.
 * This takes place when the Marvel TF series was considered by the writers to be part of the greater Marvel Universe. One more nut with Mecha-Mooks and cornball speeches was considered to be less scary than the truth. It seemed to work fine for humans, but then the 'cons found out that some dumb squishy was pretending to be their master. They were... displeased.
 * Despite being a robot himself, Ultron would certainly count. He built the Vision, Jocasta, Victorius,and Alkhema, as well as countless duplicates of himself--usually just replacement bodies for when he inevitably gets destroyed at the end of each appearance, but he has built armies of these duplicates on a couple of occasions (with the predicatable Conservation of Ninjitsu in full effect).
 * The Followers of the Light from Marvel's Shogun Warriors comic.
 * Tyranik from Archie Comics's Man Tech series.
 * The Katayanagi twins from the Scott Pilgrim series, though the building itself happens off-screen. In the comics, anyway; the film changed them to techno-themed Musical Assassins

Film

 * Dr. Totenkopf in Sky Captain and The World of Tomorrow.
 * Sebastian in Blade Runner. "They're just toys, really..."
 * Gene Simmons' Dr. Luther from Runaway not only builds killer drones, he also sabotages existing household robots so they'll go berserk on command.

Literature

 * Isaac Asimov's Dr. Susan Calvin (from I, Robot) is a robo-psychologist.
 * Victor Frankenstein, although he only ever got around to building one and a half androids (two, in the film sequel.)
 * Doctor Impossible, from Soon I Will Be Invincible, uses a wide variety of tech but specialises in robots and doomsday devices.

Live Action TV

 * Lord Dread from Captain Power and the Soldiers of the Future took over the world with robots.
 * Dr. Franklin from The Six Million Dollar Man and The Bionic Woman, who created an army of fembots.
 * Dr. Noonian Soong, creator of Data, Lore, and B4.
 * Grant Imahara on Myth Busters.
 * The Mad Scientist in "Cybernauts" episode of The Avengers builds two robots, which Steed foils by getting them to destroy each other.
 * Buffy the Vampire Slayer. Warren built the April-bot, the Buffy-bot, and finally a robot of himself.

Manhwa and Korean Animation

 * The human cast of Cubix Robots for Everyone.

Tabletop Games

 * Champions:
 * Robot Gladiators supplement. Dr. Anton Wolcott, Chief Roboticist of the Interstellar Gladiator Authority.
 * Mechanon probably counts: as a robot, he used automated factories to make improved versions of himself.

Video Games

 * Dr. Wily and Dr. Light from the Mega Man games, whose main robots are coincidentally known as Robot Masters.
 * Sonic the Hedgehog's diabolical Doctor Robotnik, whose portfolio includes trying to turn everyone in the world into a robot.
 * Lord Agony from Lock's Quest.
 * In ''Professor Layton and the Curious Village", we have Bruno,
 * Purge from Space Channel 5 Part 2 makes hundreds of robots to face off against Ulala. Apparently he's so talented, he mass-produced the Peace Carrier 8 times in under a day.
 * Robotics Masterminds in City of Heroes/Villains are playable robot masters.

Web Comics

 * Agatha Heterodyne of Girl Genius.
 * In Homestuck the Troll Equius Zahhak is quite skilled at building robots and cybernetic limbs. He does this so that he can blow off steam by fighting killer robots.
 * Rika, a British example from RPG World
 * In The Adventures of Dr. McNinja, Sean "Dark Smoke Puncher" McNinja likes to build robot animals with laser vision and stuff. Their main job is to guard the family home, but that's just an excuse--he just likes making the suckers.

Web Original

 * Doctor Steel, creating an army of giant robots, and having a robot band. And a lot of robot toys.

Western Animation

 * Jack Spicer from Xiaolin Showdown.
 * The Quintessons from The Transformers.
 * Ming's flunky Dr. Tav from the 1970's Flash Gordon cartoon. Dr. Tav invented Ming's army of Mecha-Mooks.
 * Though he has many other accomplishments, Dexter from Dexters Laboratory is constantly building robots.
 * Tobey from Word Girl, with his mega-giant-attack robots.
 * Transformers Animated's Isaac Sumdac.
 * Dr. Von Richter from Cybersix specialized in biological androids.
 * DuckTales: Gyro Gearloose. Scrooge McDuck has specifically forbidden Gyro from making robots, because AI Is a Crapshoot and his robots always seem to go berserk.
 * That said, Gyro often goes ahead and makes robots anyway for one reason or another, with predictable results. This may be a moot point anyway, as at least once he attempted to get around this by building piloted robots to get around the restriction, and rather than causing mayhem on it's own, the Beagle Boys simply stole them and caused mayhem anyway.
 * But when your greatest invention is Gizmoduck, erstwhile protector of Duckburg and oft times ally of Darkwing Duck, you get some cred.

Real Life

 * The Japanese.