Here’s a few for you,
Jane/John Doe, X, incognito, innominate, nameless, pseudo, pseudonymous, secret, so and so, such and such, unacknowledged, unattested, unavowed, uncredited, undesignated, undisclosed, unidentified, unnamed, unsigned, unspecified, what’s his/her name, whatchamacallit, you know who,
for starters.
