Character Bios are records of a certain character in each game, telling their backstory, facts, and attributes. They appear in every game excluding mobile games, except Batman: Arkham Origins Blackgate. There are 42 bios in Batman: Arkham Asylum, 32 in Batman: Arkham City, 32 in Batman: Arkham Origins, and 38 in Batman: Arkham Knight.
Character Bios in Arkham Asylum
The following characters have bios unlockable/automatically unocked.
Thomas Wayne / Martha Wayne
Tweedledum and Tweedledee
Character Bios in Arkham City
Character Bios in Arkham Origins
Character Bios in Arkham Knight
Kirk and Francine Langstrom