This thread is all about discussing the names of characters, and what we can learn about them from that.
We all know Walter has a lot of parallels with Dracula, and some are not so immediately obvious.
For instance, their names, Vlad and Walter, both derive from the german root "Wald", literally: "to rule". "Walter" and its more ancient variant "Waldihar" both mean "the Ruler of an Army", while "Vladislav" (which would later be latinized into "Vladislaus" because church people are weird) means "the Ruler of Glory" or "Glorified Prince" depending on how one stresses it. "Vlad", the simplified version, simply means "Ruler".
It's fairly common knowledge that Leon means "Lion" indicating the Belmont patriarch's courage in battle and unwavering resolve, and Richter means, "Judge", or at least it does in the High German "Rihtære", which given his final dialog with Dracula (in which he condemns the Count for his monstrous ways), seems appropriate.
But what about Mathias? Mathias is a variant on "Matthias" which in turn derives from "Matthew" which comes from the Hebrew "Mattityahu", or "Gift of Yahweh", which is probably meant to indicate his pious nature prior to becoming Dracula. His last name, Cronqvist, is Swedish and means "crown twig" which communicates that he is from a family of nobility.
However, it is also somewhat phonetically similar to the name of a real man, Matthias Corvinus, who was the king of Hungary and betrayed the real Count Vlad Dracula, and it's hard to believe the writers would have missed that.
Trevor is a Welsh name that derives from "trefmawr" which means "Big Village". With so many Germanic and Slavic names in the Castlevania canon, the presence of a Welsh name seems rather out of place. However, his name in the Japanese script, Ralph, is more appropriate. Ralph derives from the Nordic "Ráðúlfr" and its later Norman simplification, Radulf. Ráðúlfr means "The Wolf's Counsel". Fittingly, Trevor's incarnation in Lords of Shadow is associated with wolves and later serves as a counselor to Gabriel, befitting his original name.
Reinhardt Schneider from Castlevania 64 has a difficult name. While Reinhardt (with the t on the end) is not a common name, it is a variant of Reinhard, which in turn is a german pronunciation of "Reinard" which is an ENGLISH TAKE on the old German "Raginhard" which roughly means "brave/bold advice". The surname "Schneider" literally means "the one who cuts" and is a common surname in Germany and Austria. It is worth noting that Maria and Annette's surname of Renard also derive from this same Germanic root, but their given names indicate a French origin, which suggests that the families aren't directly related (but they still may be, as Reinhardt is related to the Belmonts and he does come after Richter's era, so there may be more there that it looks like at first blush).
Annette is a French diminutive of "Anna" which derives from the Hebrew "Hannah" which means "Grace", befitting her gentle personality.
Maria is an English spelling for the Greek name "Mariam", which comes from the Hebrew "Miryam" ("Miriam" also roots in this Hebrew, for you Bloodstained fans). The meaning is not known for certain, but there are several theories including "sea of bitterness", "rebelliousness", and "wished for child". However it was most likely originally an Egyptian name, perhaps derived in part from mry "beloved" or mr "love". Given what we know of Maria's personality in Rondo of Blood, "rebelliousness" seems to be apt, describing her petulant attitude towards the idea of staying behind, and continuing after Richter anyway, no matter what.
"Carmilla" is a made up name by Sheridan le Fanu, but has a root in (surprisingly NOT Camilla as you'd expect), but instead "Carmella", which comes from Carmel and the Hebrew "Karmel", which means "Garden". While not relevant in Castlevania proper, the name is plenty appropriate in the original book: Carmilla and Laura do spend quite a lot of time in the Schloss' garden.
There's a bunch of names in Castlevania, and most of them aren't just chosen because they sound good -- they all have something to say. Try digging through the names of your favorite characters. You may be surprised what you learn.