Mary Sue.

While keeping up on the response to Michael Crichton's recent book on RealClimate, I caught a reference to a literary feature known as "the Mary Sue." Identified initially in fan fiction, it is the overweeningly self-indulgent placement of an author-surrogate in a text, particularly on a text which is derived from someone else's diegesis.

The phenomenon is rendered with loving viciousness on Making Light.

Postscript: the worst of fanfic Mary Sues are being policed by this LJ community.