Sonder is the fourth studio album by British progressive metal band Tesseract. It was released on 20 April 2018 through Kscope, following Polaris (2015).

Tesseract are a British progressive metal band from Milton Keynes. The band, formed in 2003, consists of Daniel Tompkins, Alec "Acle" Kahney, James Monteith, Amos Williams and Jay Postones. The band is currently signed to Kscope. They are credited as one of the bands to pioneer the djent movement in progressive metal. As of 2023, Tesseract have released five studio albums: One, Altered State, Polaris, Sonder and War of Being, as well as two live albums, Odyssey/Scala and Portals, and the extended plays Concealing Fate, Perspective, Errai and Regrowth.