When you stethoscope or probe monsters that have names, they are referred to as “[Name] the [species]”, e.g. “Status of Fluffy the large dog:”

A pet dog named Huan will one-hit kill any lycanthrope, as a reference to the dog of the same name in The Silmarillion.

Rather than generating unnamed, the three erinyes in the game always generate with the names Megaera, Alecto and Tisiphone, which are their names in Greek mythology.

An option to have your starting pet assigned a random name. The name pool would probably come from a hardcoded list (or even a text file like engrave.txt).

Shambling horrors have randomly generated names, which give some clues about their stats and attacks.

The game tracks players with the highest death counts, and ghosts sometimes pull their names from the top 10 of this list.

Doppelgangers that transform into player monsters may adopt a name from the top 10 list when they do so (but not always). When they transform into something else, they discard the name.

Make it so that you cannot rename ghosts. (The ability to rename ghosts makes a bunch of otherwise interesting ideas about interacting with a specific named ghost boring, because you can just rename any ghost to whatever you want).

Player monsters on the Astral Plane can be named after people on the top ten list (note that they don’t all have to be; some can use the same names they have now). Possibly, pick a different name if a player monster would be generated with the player’s own name, in order to avoid problems on single-user installs where everyone on the top ten list could have the same name as the player. Then again, that could be cool.

If you can see a monster only with telepathy, you cannot see its peaceful/hostile status, so all monsters appear hostile by default (except tame monsters, which you can still see as tame). Likewise, you can’t see the monster names of non-tame monsters you can see only with telepathy.

A peaceful large dog named Sirius is found in the Ranger quest home level near Orion. Ranger starting dogs don’t have to be named Sirius anymore.

Randomized clan names for samurai player monsters (or a single randomized clan name applied to all enemy samurai in the Quest).

Track monsters that you have named. If you genocide a class of monsters that contains any you have named, notify the player of their death.