NEWT: There’s only one still missing. Dougal, my Demiguise.
TINA: Dougal?
NEWT: Slight problem is that . . . um, he’s invisible.
TINA ...Invisible?
NEWT: Yes – most of the time . . . he does . . . um . . .
TINA: How do you catch something that—
NEWT ...With immense difficulty.
TINA: Oh . . .
-- Tina Goldstein and Newt Scamander (WFT)
The Demiguise is a peaceful, herbivorous creature that can make itself invisible. It resembles an orangutan with large, black eyes and long, silky hair which can be woven into Invisibility Cloaks. The Demiguise is native to the Far East (FB).
They have the ability to foresee the immediate future, using probability. When having a premonition, the Demiguise’s eyes turn from brown to “brilliant blue” (WFT).
- When describing the power of the second Deathly Hallow, a true Cloak of Invisibility, to Harry, Ron and Hermione Xenophilius Lovegood mentions that a travelling cloak woven with Demiguise hair will hide the wearer initially but fade with the years until it turns opaque (FB).
- Ug the Unreliable, a shady goblin, organized a Demiguise Derby race and stole the takings (FW).
- Newt Scamander brought his Demiguise "Dougal" to New York City inside his magical suitcase. Dougal escaped with the other beasts, "babysitting" the giant Occamy snake-bird in a department store with a purse full of chocolates (WFT).
- Newt's No-Maj friend Jacob paid homage to Dougal with a cookie shaped like a Demiguise made in his bakery (WFT).
- Hundreds of year ago, a criminal named Phineas Fletcher set sail for North America with a Demiguise and plans to make Invisibility Cloaks. The Hidebehind came into being when the Demiguise mated with a ghoul aboard the ship (FB).
Commentary
Etymology
demi = half, lesser amount + guise = an external form, typically concealing the true nature of something
Notes
The Invisibilty Cloak that Harry noticed Mundungus carrying in OP2, and the spare Invisibility Cloak one owned by Mad-Eye Moody that Sturgis lost (OP17) could have been one made from Demiguise hair.