Tranquility Base Hotel & Casino (stylised as Tranquility Base Hotel + Casino) is the sixth studio album by English rock band Arctic Monkeys, released on 11 May 2018 by Domino Recording Company. The album was written by frontman Alex Turner in 2016 on a Steinway Vertegrand piano in his Los Angeles home. It was produced in Los Angeles, Paris and London by frequent Arctic Monkeys collaborator James Ford and Turner, alongside a wide array of guest musicians including Tom Rowley, Loren Humphrey, James Righton, Zach Dawes, Tyler Parkford and Cam Avery. Turner designed the album artwork himself, which depicts the eponymous resort with cardboard cut-outs and a tape recorder. Its title refers to Tranquility Base, the site of the 1969 Apollo 11 Moon landing.

Tranquility Base Hotel & Casino is a major departure from the band's previous guitar-heavy work, being considered less accessible than its internationally successful predecessor, AM (2013). It features a rich sound that embodies psychedelic pop, lounge pop, space pop, and glam rock, as well as elements of jazz. It also draws influence from soul, progressive rock, funk, French pop and film soundtracks of the 1960s. Instrumentally, it incorporates vintage synthesisers and keyboards, including organs, pianos, harpsichords and the dolceola, as well as the Orchestron, Farfisa and RMI Rocksichord. Baritone and lap steel guitars are introduced by the band on multiple tracks, in addition to the electric and acoustic guitars typically used by the band, as well as a variety of percussion instruments, including rotary timpani and vibraphones. Its lyrical content draws heavily from science fiction and film, exploring consumerism, politics, religion and technology through the concept of a luxury resort on the Moon told from the perspective of various characters, such as the singer in the in-house band on "Star Treatment" or the hotel's receptionist called 'Mark', whose name is directly referred to in "Tranquility Base Hotel & Casino" (the title track) and many other times throughout the albums lyrics and visuals.

Despite its stylistic deviation polarising listeners, Tranquility Base Hotel & Casino was released to generally positive reviews and was named the best album of 2018 by Q magazine. It was nominated for the 2018 Mercury Prize and the Grammy Award for Best Alternative Music Album. The single "Four Out of Five" was nominated for Best Rock Performance. It became the band's sixth consecutive number-one debut in the UK, the country's fastest-selling vinyl record in 25 years, and the band's third top 10 album in the US. It also topped the charts in Australia, Belgium, the Netherlands, France, Greece, Portugal, Scotland and Switzerland. Following its release, the album was promoted by the singles "Four Out of Five" and "Tranquility Base Hotel & Casino", as well as a global tour and multiple television appearances.