Yes, the movie American Sniper is based on an auto-biographical book written by "the most lethal sniper in the history of the American military", Chris Kyle.
The book is rather interesting for more than just its narrative - it was also the subject of a $1.3 million lawsuit, which Kyle's widow was forced to pay out after the soldier's death.
In the book, Chris Kyle claims to have punched former governor of Minnesota and former pro-wrestler Jesse Ventura.
The book earned Kyle over $6 million, and the rights to the movie are likely to multiply those earnings, so in the long run the lawsuit might end up looking like small change!