Blandy

Blandy is an evil creature whose sole purpose is to specifically pit Earthlings into jealousy. She is known to be a shapeshifter, due to how she changed back to an original form. She has distinct features to that of Billy (an example is the large nose) and small stature when in disguise. Billy fell in love with her, but she fell in love with Grim, thus making Billy enraged. Billy thrashes Grim for a while, even though Grim didn't like Blandy at all. Mandy appears while hearing of Blandy in one of Grim's books (during which Harold was reading, or specifically looking at the pictures). She is sent to go back to the underworld, however in the later part of the episode she appears again, and she again thought she was marrying Grim instead of Billy (a marriage scene can be viewed at the end), which repeats the beating of Grim.

Blandy is voiced by Richard Steven Horvitz, strangely enough.