Anna was a Human female.

She was the sole survivor of a Terellian freighter crash landing on an unnamed class M planet. For seven years, she lived alone on the planet until there was another crash. The survivor of that crash was a Human male, whom she nursed back to health. They fell in love. Several years before 2370, the Iyaarans discovered the remains of the freighter. Within the ship, they found Anna's logs, from which they learned of concepts alien to their culture – love, antagonism, and pleasure. (TNG: "Liaisons")

This character was only mentioned in dialogue.
The woman, whose name was not given in the episode, was identified as Anna at and in the Star Trek Encyclopedia (4th ed., vol. 1, p. 30).