Anatomy of a memorable monster name
The best monster names combine aggressive phonetics with mythological resonance. Hard consonants like K, X, TH and Z generate immediate auditory impact. Pyraxis sounds more threatening than Pyro because the terminal X implies something alien and dangerous.
Latin suffixes like -us or -ax grant mythological gravitas: Abyssus, Mortifax. Prefixes like Mal-, Necr-, or Chthon- activate associations with darkness or death. Common mistake: generic names like 'Dark Beast'. A specific name like Nyogtha the Crawler evokes behavior and form.
Length matters. 2-3 syllable names (Dagon, Scylla) are more memorable for recurring NPCs. 4+ syllable names (Nyarlathotep, Azathoth) work for cosmic entities rarely invoked directly. Including a descriptive title ('the Devourer', 'the Withered') completes the identity without requiring explanation.
Adjusting names by game system
In D&D 5e, monsters with complex names are typically reserved for CR 10+. A CR 3 aberration might simply be called Grell, while a CR 23 demigod deserves Orcus, Demon Prince of Undeath.
For Call of Cthulhu, unpronouncability is part of the horror: apostrophes and strange consonant combinations (Shub-Niggurath, Y'golonac) reinforce that these entities exist beyond human language. In Warhammer, names often include Germanic titles: Archaon the Everchosen, Nagash the Supreme Lord of Undeath.
For video games, consider that names appear in health bars and menus: Malgoroth is more legible at 16px than Ny'arlgrthep'xul. Final boss names must be epic but typeable: players will be typing them in forums for years.
Avoiding exhausted genre clichés
Overused suffixes that weaken impact: -thor (saturated post-Marvel), excessive -ius (sounds like high school Latin), -death or -kill endings (too literal). Deathkill the Destroyer is involuntary self-parody.
Major cliché: generic 'dark' names. Darkthorn Shadowblade doesn't generate fear, it generates laughter. Same with unnecessary apostrophe accumulation: D'ar'k'th'or'n looks like a broken keyboard. Effective horror comes from specificity: Bokrug (who dwells beneath the waters of Ib) is more unsettling than Aquademon.
Also avoid perfect symmetry: Xanax sounds more like a pharmacy than a monster. Asymmetric names (Cthylla, Tsathoggua) generate phonetic tension. And not every monster needs to sound evil: The Thing on the Doorstep terrifies precisely through its neutral description.
Building mythology around the name
A strong name enables instant worldbuilding. Rhan-Tegoth (Lovecraft) suggests pre-human antiquity through phonetics alone. You can reverse the process: start with the monster's behavior and derive the name from there. A creature that paralyzes with its gaze: Petraxis (petra + axis = stone axis).
Compound names reveal cultural evolution: in your world, Dreadmaw might be the common name villagers gave it, while scholars call it Carcharadus Nocturnis in their tomes. This duality adds depth: folklore vs. academic taxonomy.
For long campaigns, let names have consequences. If they defeat Mortifax the Eternal, the next cult might attempt to summon Mortifax Renatus. Names become legacy, scars in the world's history. A town might be called Scyllathor's Valley because the beast fell there 300 years ago.