I'm always 
when I see my name on these threads - I agree it's not wonderful, tbh, but every so often I see people suggesting it's going to make a comeback. Maybe when its toxic political associations have faded a bit more ...
Surprised to see Leon mentioned as a retro name. That's never been a common name in the UK, until maybe very recent times. It's a Spanish name, isn't it? And possibly a bit less unusual in the US. Leo was a very unusual name and rather posh until quite recently. Leonard is the one that was moderately popular a couple of generations ago and would therefore be retro now. There's also Leopold, which has royal associations, but has never been much used generally to my knowledge and long may that continue. Bit too much like Leopard to my mind.
Retro names from my parents' generation (i.e. born in the 1920s and 30s): Mavis, Doris, Doreen, Kathleen, Ronald, Edna, Edith, Jill, Geoffrey.
Elizabeth, Katherine, William, James, John and other classic names never, ever drop out of the top 100. They may bob up and down a bit but they have never fallen out of use and I don't think they ever will. Everybody knows those names, they are easy to spell, easy to pronounce, they have lots of popular short forms and associated nicknames and lots and lots of historical/family associations.