It depends. Names for people and locations get reused all the time, both in real life and in fiction and of course it's fine to do so. At this point, it's probably impossible to be 100% original all the time with the amount of books, games etc that are out there. However there are some names that are so iconic that people will immediately connect them with a certain work. For example I wouldn't write a fantasy novel and name a city "Minas Tirith", as everyone will just think of LOTR. But calling a city, say, "Dragonstone" is just fine IMO, even though it's a place in ASOIAF (and probably more than a few older fantasy books).

Could you clarify what you mean by work? I think you're talking about a creative work like a novel/video game/whatever

It depends, if it's not satire, having the full cast of Star Wars by name is pretty sketchy stuff, even if they are in the Friends storyline.

But not being able to use New York because someone else has is a silly thought.

I mean, if you write a western with a character called Luke Skywalker, on a planet called coruscant, it's pretty bad because it's just shitty writing unless you're doing a direct spoof.

Now, a western with Luke Skywalker, on a planet called tatooine, with him as a gunslinger recruited by a marshal to go after a notorious bank robber and killer that turns put to be his dad? That's good because it's doing something interesting, but expect to hear lawyers.

My rule for whether or not something is fair in that regard is who profits.

A big company, idgaf at all. A single writer/creator, maybe don't reuse their names because it's kinda shitty to rip off an actual creator rather than investors. But even then, if you're not trying to ride their coattails, idgaf