...huh, why didn't we ever get a Belmont in Smash, come to think of it
Richter would be the obvious choice, but he never showed up in a Nintendo release, so Simon or Trevor maybe?
Alternatively, Soma Cruz could represent the series. Aria of Sorrow was one of the most well-received games in the series, after all.
kinda hoping to see castlevania represented in the next smash but with konami doing whatever the fuck they're doing that seems unlikely