A person who holds and can exercise a power of appointment.
EPTL 10-2.2(b) defines a donee:
§ 10-2.2 Other words defined
. . .
(b) Donee. A donee is the person to whom a power is given or in whose favor a power is reserved.
Restatement (Third) of Property § 17.2(b) defines a donee:
§ 17.2 TERMINOLOGY ASSOCIATED WITH A POWER OF APPOINTMENT
. . .
(b) “Donee.” The “donee” (“power holder”) is the person on whom the power of appointment was conferred or in whom the power was reserved. If the donor reserved the power in himself or herself, the donor is also the donee, and the term “Donor-Donee” is sometimes used to refer to such a person.