The Nesk are a race of aliens in the fictional Animorphs books by K.A. Applegate. They are actually made up of thousands of intelligent ants that join together to form into the shape of a body capable of using the technology they have stolen from other species. They lived on Earth 65 million years ago, and constanly waged war against the peaceful Mercora . The Nesk appear in .

When they are finally beaten and have to leave Earth, the Nesk divert a comet so it hits Earth's surface, thus wiping out the Mercora and the Dinosaurs. The Animorphs reluctantly allow this to occur so that their timeline may continue without interruption.