Voldemort just seems like the perfect evil villain name. It’s got that "mor" sound that all villains have. Well, maybe not all, but quite a few: Moriarty, Morbius, Mordred. Morpheus in The Matrix wasn’t a villain, but he was ominously scary. And there’s "mor"e:
Frodo Baggins went through the mines of Moria to get to Mordor, where he met Sauron, who, as great a villain as he was, started out as the lieutenant of Morgoth, the original and darkest villain in the world of Tolkien's Middle Earth.
H.G. Wells sent his time traveller into the future to encounter a cave-dwelling evil race called the Morlocks. He also created an evil genius called Dr. Moreau.
The syllable "mor" is a phonestheme, which is a word part that carries connotations due to association. The Week looks at mor” and other phonesthemes and how just a couple of letters can get a reputation of their own.