ghostessn.

1651 J. Harington Hist. Polindor & Flostella ii. 49 O doe not passe me Deare Ghostesse, sweet, but first imbrace me.

1801 B. Frere Man of Fortitude I. ix. iii. 156 I'll be shot if I don't bring back, in a couple of hours, all the ghosts and ghostesses of the place, bound neck and heels.

1898 ‘H. Stretton’ Soul of Honour (1905) vii. 69 A porter from the station told me he'd seen Miss Phebe, and I said he must ha' seen a ghostess.

2005 Philadelphia Inquirer (Nexis) 12 Sept. It's in their travels that they encounter more garden-variety evil, such as a particularly unattractive ghostess named Bloody Mary.