Want some picture books for possible mentor text? Try this or this one.
Scroll down and you'll find Marcie Atkin's suggestions for mentor text for biography.
On Mr. Locks' site you'll find mentors for biographies.
Two Writing Teachers in this blog suggest a book that will take biography "to a new level."
A unit of study from California that uses mentor text.
From History Fix comes a lesson on biography that includes mentor text and student exemplars.