A Villain Named Zrg

Be it because of its outlandish sound or its harsh structure, there seems to be a trend of naming sci-fi villains—and especially stereotypical ones—after these three consonants (sometimes with a K instead of a G), with a random vowel in-between and possibly some letters before or after.

Compare Law of Alien Names, Xtreme Kool Letterz, Names to Run Away From Really Fast.

Examples of A Villain Named Zrg include:

Anime and Manga

King Zarkon from Voltron would be a near-example.
Zork from Yu-Gi-Oh!
- Also the cards "Dark Master Zorc" and, flipping the letter order, "Gorz the Emissary of Darkness."

Comic Books

Spoofed in Spirou and Fantasio with Zorglub (portmanteau of Zorg and "Arglub" which is a standard Written Sound Effect for accidental strangling in Franco-Belgian comics). Notable in that it is currently the older example known—even before Starcraft—and already a parody.
Calvin and Hobbes loved this trope. Besides the evil aliens called the Zorgs, there were the Zargs, Zorkons, Zogwargs, and Zogs (close).

Film

The Fifth Element: Jean-Baptiste Emmanuel Zorg. Especially significant as the whole movie is a reconstruction of sci-fi movies and comics of the 1970s and 1980s.
In the film Zathura, the evil lizard race are called the Zorgons.
A case of Aerith and Bob occurs in Betty Blue, where Zorg is a perfectly normal handyman in the France of the Eighties.

Literature

Emperor Zhark from the Thursday Next books is a near-example (in two different ways). He's the villain of his own pulpy sci-fi series, but in the metafictional main story, he's one of the good guys.
The Ax Crazy Prince Serg from the Vorkosigan Saga might count, because his name is pronounced "zerg".

Live Action TV

Babylon 5 has a humanoid predator species named Zarg.
Barizorg from Kaizoku Sentai Gokaiger. The name is presumably a corruption/portmanteau from 'cyborg'.
Zurgane from Power Rangers Ninja Storm.

Newspaper Comics

Inversion: Hans Zarkov from Flash Gordon, who's one of the good guys.

Toys

Transformers has the Decepticon Scorponok's head, Lord Zarak.

Video Games

StarCraft: What four tropers out of five thought when seeing the title.
Zorg: An alien race in the video games Strange Adventures in Infinite Space and Weird Worlds: Return to Infinite Space.
- They weren't exactly villains, though. Just... alien.

Western Animation

The archnemesis of Buzz Lightyear in Toy Story 2 is called Zurg. Another reconstruction, by the way.
Space Ghost's arch-nemesis Zorak.
The alien villain in Space Chimps is named Zartog.