Witch Martha is a female anthropomorphic orangutan and a witch.
This witch gathered with Witch Hazel, Witch Goofy and Witch Phyllis on Halloween Night in 1952 to brew a potion together in the Haunted Mansion. Phyllis then set her three comrades loose on Duckburg: Witch Goofy took the East Side, Witch Hazel the "dull" part of town where Donald Duck lives, and Martha was sent to the North Side.
Behind the scenes
Witch Martha appears in the 1972 The Mouse Factory episode Spooks and Magic. She was portrayed in live-action by a costumed performer who is not credited in the closing crawl. Interestingly, the costume used appears to be a fixed-up version of the costume used in the Disney Parks for King Louie.