Infest the Rats' Nest is the fifteenth studio album by Australian psychedelic rock band King Gizzard & the Lizard Wizard. It was released on 16 August 2019 by the band's record label, Flightless, and ATO Records. The album sees the band using a heavy metal and thrash metal style, which they had only briefly touched upon on previous albums. Its lyrics address environmental themes such as climate change and ecological disaster through a cli-fi narrative involving space colonization.