Anna is the woman who rescues Jean-Luc Picard after a shuttle crash in Liaisons and declares her love for him, but who is really the Iyaaran ambassador Voval in disguise.
Anna appears in the seventh-season episode Liaisons. Picard is travelling to the Iyaaran homeworld with the pilot Voval when their shuttle comes down on a barren planet. He wakes in the wreck of an old Terellian freighter, tended by a human woman who says she has been stranded there alone for seven years.
Anna is devoted to him almost at once. She tells him his ribs are broken, hides the means of calling for help, locks him in and finally threatens to throw herself from a cliff if he will not love her.
Picard notices the inconsistencies and calls her bluff, whereupon she changes into Voval. The Iyaarans have no experience of love, and the ambassador staged the whole affair, modelled on a real castaway's diary, to study it at first hand.