Dr. Genericius

By some weird reason, wizards and Mad Scientist types often have names ending on "ius" (possibly just "us", but "ius" is just better). It makes their names sound more smartass and in the same time Badass.

Truth in Television with Vesalius and all of the other Medieval/Renaissance scientists who used Romanized names (Keys would become Caius, to cite a real-life example), the likely inspiration for the trope. It's frequently Canis Latinicus, though.

Comic Books

Spider-Man: Dr. Otto Octavius.
Dr. Cornelius from X-Men. (He's the other guy responsible for Logan becoming Wolverine.) ^[1]
Dr. Michael Morbius, a Professor Guinea Pig, became a Living Vampire.

Film

Dr. Morbius in Forbidden Planet
Dr. Pretorius the mad scientist from Bride of Frankenstein.
There is a Dr. Vesalius in the Vincent Price movie The Abominable Dr. Phibes.
Dr. Cornelius and Dr. Zaius from Planet of the Apes.

Literature

Doctor Faustus.
Also Dr. Cornelius from The Chronicles of Narnia, a magician though not an evil one.
Dr Igneous Cutwell, from Mort, is another non-evil wizard, and is unusual in that it's his first name that fits the trope.
The Vesper Holly series has Dr. Desmond Helvetius
Harry Potter, of course. A lot of wizards have names ending in "us" : Albus, Lucius, Regulus, Remus, Rubeus, Severus, Scorpius, Sirius... It seems to be more frequent in the Pure-Blood families, though.
Joseph Sheridan Le Fanu's Occult Detective Dr. Hesselius.

Live-Action TV

Dr. Cornelius from Doctor Who - a name which actually sounded somewhat jarring because of this very trope, given that he's an ordinary medical doctor.
Dr. Gaius Baltar from the 2004 Battlestar Galactica. (In the original version he was only "Baltar" and was not a doctor.)

Music

Professor Psychoticus, Mike Barson's alias when Madness were pretending to be The Dangermen.

Video Games

Dr. Nefarious from Ratchet and Clank.
Dr. Mordin Solus from Mass Effect 2.
Dr. Mobius and Dr. Borous from Fallout: New Vegas.

Web Comics

Order of the Stick: Vaarsuvius, Aarindarius. And then subverted by Inkyrius, an apprentice baker.
- And of course Elan goes on to rename himself as Elanalicious.
Professor Odious from Everyday Heroes.
Subverted in Last Res0rt when Gabriel Damascus ends up being a Doctor... except his name is actually Gabriel the Maskless.
- Other doctors in the comic include Qin Xu and Daisy Archanis.

Web Original

The Descendants has Doctor Paralus, which is his actual name but the heroes are constantly mocking it as Powerless or Perilous. A Bad Future is shown where he does in fact become Doctor Perilous.

Western Animation

Professor Calamitus in Jimmy Neutron.
Another Dr. Pretorius in Felidae.
- His name is Preterius in the German original. Still fits this trope though.
Yet another Dr. Pretorius in The Mask animated series.
Venture Brothers: Dr. Byron Orpheus.
Dr. Anton Sevarius from Gargoyles.
Dr. Malignus, a minor recurring villain from Teenage Mutant Ninja Turtles (2003).
Dr Colossus, a throwaway gag from The Simpsons.

Real Life

Dr. Viktor Capesius, Doctor of Pharmacy, physician and pharmacist in the Auschwitz death camp and right hand man to another Mad Scientist, Dr. Joseph Mengele.

↑ Most versions of the story depict a bald Asian guy and a red-haired or brown-haired, bearded guy working on the soon-to-be Wolvie. The bearded guy is Dr. Cornelius. The bald guy's the one who invented the adamantium bonding process, and Lady Deathstrike's father. He shows up more often and is more recognizable, in the comics and animated versions.

[1] Most versions of the story depict a bald Asian guy and a red-haired or brown-haired, bearded guy working on the soon-to-be Wolvie. The bearded guy is Dr. Cornelius. The bald guy's the one who invented the adamantium bonding process, and Lady Deathstrike's father. He shows up more often and is more recognizable, in the comics and animated versions.

[1]