Intelligent undead range from the fairly dim ghouls to the often very intelligent vampires and liches. They are usually capable of reproducing, although the mechanisms that achieve this are often unknown. Ghosts are the exception to this, they are highly variable in their forms and abilities and are not capable of reproduction. Liches also can't reproduce, as they are created by powerful magic.

Ghasts

Ghosts

Ghouls

Liches

Vampires

Vampire Spawns