Not the movies but the story of the original novel itself. As the original story details Robert Neville has so many Moral Event Horizon moments he has numerous mental breakdowns throughout the 1st 2/3rds of the story. So it can be assumed that by the storys pivotal end Neville doesn't know what is truly fiction in his own mind and reality. However in actuality Neville is nothing more now then a serial killer and madman who has probably killed more people then anyone else in New York's history thus making him a Legend.