There are certain names that for me fit this category. [name_m]Elvis[/name_m] used to be one until I fell in love with [name_m]Elvis[/name_m] [name_m]Costello[/name_m]’s music.
Madonna.
Lady Gaga.
Cher.
Wondering what names others hold as just for one famous person.
Adele definitely came to mind, although I have met an [name_f]Adele[/name_f] in real life!
Jezebel - her legacy is just…ugh.
I have too- a lovely older philanthropic lady.
Beyoncé and [name_f]Oprah[/name_f] spring to mind!
Shakira is the first one I thought of. I don’t like the name or her music though.
Elsa
Me too! The Adele I know (and I’ve known her her whole life) is a young teenager now, maybe about 14? No nickname, just Adele. Sweet kid. Born and named just before the singer Adele became popular in the US; it’s a family name for them so pure coincidence. Because I’ve known an Adele since before I met the singer, this has never been one of those “single person” names for me.
As for other names not mentioned yet:
Prince
[name_m]Bono[/name_m]
[name_m]Elvis[/name_m]
[name_f]Cher[/name_f]
Most of the ones I thought of have already been suggested.
I would add:
[name_f]Britney[/name_f]
[name_f]Shania[/name_f]
[name_f]Rihanna[/name_f]
[name_m]Tupac[/name_m]
Björk
[name_m]Drake[/name_m]
[name_m]Kanye[/name_m]
Pelé
[name_f]Enya[/name_f] (though TBF I have met a woman who has a daughter with this name)
Well real or…? Anyway, here are a few characters
[name_f]Hermione[/name_f]
[name_f]Katniss[/name_f]
[name_f]Annabeth[/name_f] (I think you could use this if you were brave enough)
[name_f]Cinderella[/name_f] (?)
[name_f]Cady[/name_f]
[name_f]Cher[/name_f]
[name_f]Leia[/name_f]
[name_f]Lorelai[/name_f] ([name_f]Lorelei[/name_f] is okay)
And I feel like the surname of famous celebrities, [name_f]Anniston[/name_f] springs to mind, are also not very usable.
And some real people…
[name_f]Cher[/name_f]
[name_f]Madonna[/name_f]
[name_f]Rihanna[/name_f]
[name_f]Shakira[/name_f]
[name_f]Beyonce[/name_f]
[name_f]Solange[/name_f]
For whatever reason I’m really blanking, and on another day could come up with so much more but… this is what I’ve got today.
Who is the famous [name_f]Annabeth[/name_f] 
[name_f]Annabeth[/name_f] [name_u]Chase[/name_u] from [name_u]Percy[/name_u] [name_u]Jackson[/name_u].
Why [name_f]Cady[/name_f]?
I want to say [name_f]Zendaya[/name_f] but this name is actually in the top 1,000 in the US so people are obviously using it 
I don’t blame them, she is so awesome! But it seems like a one person only name to me.
Also, Lizzo. I can see it used as a nickname for [name_f]Elizabeth[/name_f] or something tho!
Definitely Beyoncé. Others I can think of are…
Shakira
[name_m]Kanye[/name_m]
[name_f]Dolly[/name_f]
[name_f]Rihanna[/name_f]
[name_f]Oprah[/name_f]
[name_m]Prince[/name_m]
[name_u]Paris[/name_u]
It’s pretty unique and is the name of the main character in Mean Girls. It’s not unusable, but I feel like someone would get, “Oh like [name_f]Cady[/name_f] from Mean Girls,” a lot if that was their name.
Flordelis 
I feel weird for not knowing so many of these associations
p!nk is the only one i can think of that hasnt been suggested yet