I'm actually happy to see I'm not the only person that preferred DXC's version of Maria (though she is my least favorite character from the Dracula X series).
I'll go by game (for those I care to mention):
Castlevania -Super CV IV: The Bats, Medusa Heads, and Crows. So many pits...so much time being knocked into them... For CV II though, it's the townspeople. Their advice is so useless...
Dracula X/SOTN: Maria. As mentioned before, I just found her to be quite useless as a whole and it seemed like they gave her transparently bad reasons for even being there, let alone being important at all. As for the Rondo version, the anime inspired vibe only made her existence seem worse: she was far too cutsy in appearance, VA, and overall tone. Coupled with her very odd powers of having animals fight for her and it just made her laughably bad. Though the powers seemed a bit better in SOTN, it still seems out of place.
CotM: Hugh. Jealous d-bag.
HoD: Juste. To be honest I'm not sure why but I just didn't like him that much. Maybe because he seemed like Alucard-Lite. His personality was pretty bland as well.
AoS: To be honest, I found everyone but Soma, Alucard, and J. pretty useless. Mina was just a-typical I-am-but-not-really love interest that gave some information (like with Hammer, anyone could have done that), Yoko was just...there and Hammer set up shop but honestly, they could have had anyone do that. And Graham was pretty bland as well.
DoS: See AoS. Unless you count the non-canon ending...then everyone actually had a purpose. But by far, the villains were worse. Maybe the artwork rubbed off on the personalities (anime) because they were like Team Rocket without any of the fun humor: they were just flat out lame and very shallow characters with very cliche` personalities for their roles.
PoR: Charlotte and Johnathan 'No Problem' Morris. They're just very bad anime cliche` characters, from design to personalities, to actions. Even the final battle after they beat Dracula and Death...I just wanted to punch Charlotte for her stupid 'team work' banter she gave them.
LoI: I don't really dislike anyone so much as I dislike the melodramatic fashion every acted in. I laughs far too much than I should have. XD
CoD: St. Germain (SP?) because he was just very out of place, even as a time traveler it just felt odd for him to be there. Issac just made me...uncomfortable after a while. Like he was FAR more into to Hector than he let on---but on a far darker, creepier level. Plus when he stabbed Trevor...seriously, Issac is just unsettling. LOL But I don't hate him...I'm just O_o about him.
Judgement: Aeon. He seemed like more of a reason to excuse St. Germain's existence more than anything else. (The whole time traveler's/watchers of time/whatever thing) His design doesn't bother me (even if he did look like L's older brother from Death Note) too much until we got to the black lipstick. Didn't really understand that one. LOL.
LoS: Gabe, mainly because of who he's actually suppose to be. I like my Dark Lords evil, sitting on thrones, and tosses glasses of blood while screaming "Have at you!". Though I wasn't a big fan of too many of the characters in this game. (...or the story for that matter...)
I like a lot of your points. I'll post mine like that, since all I had to say was "Dmitrii".
CV (and all of its remakes)+CV2: I'd have to say the same about this one. Except for the villager part. It wasn't the villager think that aggravated me. It was how half-assed the bosses were in
CV2. Three severely limited bosses. -_-
Dracula X Chronicles: Overall? I'd have to say Shaft. He was pretty bland and only thought of "Master this" and "Master that". And then said things that didn't make sense like, "Belmont? How can you be here? Blast it. Very well!" And then teleported. When of course, later he decides to take you on. I don't see why he didn't just do it there. Of course,
Dracula decided to completely leave out the fact that the
Succubus's opponent happened to be his own son. >.>
Circle of the Moon: Morris. He was utterly useless.
Harmony of Dissonance: Maxim. He was fail all the way, and kind of a
jealous d-bag just like Hugh.
Aria of Sorrow: Yoko. As cool as she was, she was useless.
Dawn of Sorrow: Hammer.
Hammer shouldn't be some guy with a puppy love crush for
Yoko. He was a badass in
AoS. Come on, what is this?
Portrait of Ruin: It was
Vincent. All he did the entire game was complain.
Lament of Innocence: I think
Rinaldo. "You're going in there to destroy the Vampire that locked me away in darkness, and avenge my daughter. Doesn't matter, the potions are still 500 gold." Seriously? What a jerk.
Curse of Darkness: Hector. He was dense, made stupid comments, jumped to so many conclusions, etc. And he had a fat face. "So... those two are enemies..." Astounding observation from
Hector.
Judgment: Maria. Come on.
Maria is one of my favorite characters in the series and you had to go and ruin her and turn the entire game into some stupid anime fighter because all she cared about were boob sizes. >.>
Lords of Shadow: Haven't played the game yet (played demo though), but I'd have to say the talking unicorn from stage 2. That just threw me off.