 Animorphs Chronicles

The Animorphs Chronicles is a series of 4 books written by K. A. Applegate alongside the main series as a companion collection to detail the backstories of characters introduced in the series, and help explain and expand upon concepts that were briefly defined in the series, but, as the series is told from a human point of view, were limited in terms of what could only be explained through in-story dialogue.Four "Chronicles" books were published; "The Andalite Chronicles" in 1997, "The Hork-Bajir Chronicles" in 1998, "Visser" in 1999 (the only Chronicles book not to feature the words "the" or "chronicles" in its title), and "The Ellimist Chronicles" in 2000.