A Persona is the fictional historical personage portrayed by a participant in the SCA. One's persona can be as simple or as complex as desired: some personas are given elaborate back-stories and supplemented by meticulous research; others are merely a name and rough century based on the player's preferred clothing or armor style.
Often, one's persona changes throughout their time in the SCA, reflecting changes in interest and focus.
Generally, the only limits placed on personas are:
In addition, you cannot choose any names that are offensive in the modern context. For example, the German surname Judenfeind, or “Enemy of the Jews”, is a perfectly period last name, but due to it's connotation with a short, very angry Austrian man with a bad mustache, it is prohibited. Other names may be completely innocuous, but due to some particular connotation are prohibited. An example of this is the name Edmund Fitzgerald, due to it's association with the famous sinking of the Ore Carrier of the same name. (Note from Dietrich: This name was, in fact, registered, as apparently it was only famous in Ealdormere and Æthelmearc. Nevertheless, the principle stands. Talk to your herald today.)