the Simon Wraith from Harmony of Dissonance was called a Hellmont in Harmony of Despair and it states "Some say this is what happened to Simon Belmont in the end."
Some monsters would like you to believe that when a Belmont or other heroes dies, their bones are brought to the castle, flesh forms around them, and they can be controlled like any other zombie by the castle's influence. Of course, those zombies are called "Fake" in the game (even the Japanese versions apparently), but I've still wondered if they were really fake from time to time.
Dracula did indeed desecrate the corpses of Christopher Belmont's parents in Belmont's Legacy. Poor souls.