The Name of Doom
How's this for a literary murderers' row?
The root "mor" is English literature's surest marker of dread. The classic examples above have rooted themselves so deeply in our culture that storytellers can tap into their sound for ready-made villainy. Videogames and comics are rife with diabolical Mordacks and Mordos.
The mor names also tap even deeper veins in our language. The names' individual origins vary. For instance, the mor in Moriarty comes from the Gaelic muir ("sea"), the mor in Moreau from Mauritania, and the mor in Morrigan probably from the same ancient root meaning "terror" as in the word nightmare.
But critically, all of these mors coincide with the Latin mors, meaning death. That root is ubiquitous in modern language, including English words like mortal, murder, moribund, and mortify.
On the face of it, then, the murderous mors seem like simply a part of our language of death. That would make them a rare example of names' cultural meanings arising directly from their linguistic derivations. But I think there's another piece to the puzzle. Consider this alternate list of English mor words:
These positive terms, too, derive from powerful Latin sources. Amor is love, familiar from French amour, Italian amore, and more and more amor. Mores means conduct and morals. Yet neither of these admirable words has had much impact on English names, real or fictional. Amanda (via the Latin for "lovable") and actress Dorothy Lamour are as close as it gets.
In the world of names, then, death has triumphed over love and morality. And the path from linguistic origins to names seems to be paved with names themselves. Every Mordred and Voldemort strengthens the link between mor and mortality.