A blob monster composed of green, translucent slime with the skull of an anthropomorphic duck suspended in it, the Blob was a resident (or at least an employee) of the haunted Hazel House in Duckburg. Along with the other monstrous inhabitants, it took part in an annual scheme meant to scare trick-or-treaters out of their candy to compensate for the lack of candy stores open at night. Acting mainly as the "crew" of the production (with a hat to match), the Blob did have a small role in the actual scaring as one of the various creatures lurking in the corridor of doors (the rest being props operated by Frankenstein).
After the scheme was revealed in 2020, the Blob packed up the various equipment that it had been operating (including a fog machine) and left, seemingly uninterested in attempting to eat Huey, Dewey, Louie, and Webby with the other monsters. It did not visit McDuck Manor with them to trick-or-treat after amends were made, either, nor did it appear in the apparently-supernatural portrait of the Ducks and Hazel House monsters posing together which was hung on the wall of the house.