Planet of the Apes: Extinction was a proposed follow-up novel to Planet of the Apes: Force and Planet of the Apes: Resistance - both written by John Whitman - and Planet of the Apes: Rule, written by J.E. Bright but unpublished due to poor sales. A chapter-by-chapter story outline for Extinction was written by Whitman, and it would have been published by HarperEntertainment as part of their on-going series of Planet of the Apes spin-off novels.
Decimated by the ape's destruction of their city, Karubi and Daena led the last human survivors on a desperate trek through a tunnel system inside a mountain, attempting to escape Thade's pursuit. The tunnels, however, were home to giant carnivorous beetles, lethal to both ape and human alike. Only a truce between Attar and Karubi could save their lives. Other characters featured included Krull and Ari
- Extinction was given the code ISBN:0060098880, to be published by HarperEntertainment in August 2002.