The Stranger

The Stranger is the name used to generally refer to the protagonist (the player) of the Ultima series. After Ultima IV, however, this hero was specifically called the Avatar.

From Ultima I through Ultima IV, the Stranger could be male or female, or "other" in Ultima III, under any name the player wished. Before Ultima IV, the Stranger was not always human; the player could choose from several races. In Ultima IV, the Stranger completed a series of quests to become the Avatar, the embodiment of The Eight Virtues and the true hero of Britannia.

Although it wasn't explicitly mentioned in Ultima IV, from Ultima VI onward, it was clearly stated that the Stranger was the person who would become the Avatar, thus preserving continuity.