Ghoul

Ghouls are humans who have somehow rotten flesh and have lost their minds, therefore acting with their primal insticts. They are similar to, but not the same as, zombies.

Castlevania: Dawn of Sorrow
On the "Hard" difficulty, ghouls move faster and can poison you.

Castlevania: Order of Ecclesia
In Order of Ecclesia, ghouls appear in the Dracula's Castle stage, and can poison you, the same ability they had in Castlevania: Dawn of Sorrow.