If done well, the names fall into history.
1) Frankenstein. Aside from the debates about the monster not actually bearing this name, Doctor Frankenstein (exaggerated with a German accent, of course) bears significant nasal sounds (N) alternated with other powerful sounds like the Fr, k, and st.
2) The House of Slytherin. This is an ingenious name. Of course, this name plays on "slithering," as in a snake, and brings to mind creeping and maneuvering that is close to the ground. But say it out loud. When you say this word slowly and carefully, it is, quite frankly, something that forces your teeth to bear and your nose to wrinkle. Quite effectively.
3) Cruella DeVille. This name plays well on "cruel," of course, but the repeated Ls and Rs (liquids, which I may touch on next time) give a slightly smooth and creepy feel to the name. "DeVille" is a name associated with tradition and history from cars to science, and the character name evokes a cruel, liquid, smooth tradition.
Not bad. Rather evocative.
That song helps a bunch.
Enjoy some powerful, poignant sounds this Halloween!