Outside (stylised as 1. Outside and subtitled The Nathan Adler Diaries: A Hyper-cycle) is the 20th studio album by the English musician David Bowie, released on 25 September 1995 through Virgin Records in the United States and Arista Records, BMG and RCA Records in other territories. Reuniting Bowie with musician Brian Eno following the late 1970s Berlin Trilogy, the two were inspired by concepts "outside" the mainstream, such as various outsider and performance artists. Recorded throughout 1994, the experimental sessions saw Bowie conceive a world where "art crimes", such as murder, pervade society. The resulting Leon project initially faced resistance from labels due to its uncommercial nature. The project's bootlegging led to additional sessions in 1995 to revise the concept and record more commercial material, inspired by a diary Bowie wrote for Q magazine.

Influenced by the television series Twin Peaks, the nonlinear narrative of Outside concerns the residents of the fictional Oxford Town, New Jersey, and follows detective Nathan Adler as he investigates the murder of a 14-year-old girl. The tracks show perspectives of specific characters, while spoken word between-song segues convey more character ideals; the story and Adler's diary entries were presented in the album's CD booklet. Musically, Outside displays styles from art rock, industrial rock and jazz, to electronica and ambient. The album cover is a self-portrait of Bowie.

Released at the height of Britpop in the UK, Outside received mixed reviews from critics. While most praised the music, others found the concept pretentious and hard to follow. Nevertheless, many considered it Bowie's finest record since 1980's Scary Monsters. Outside peaked at number 8 in the UK and number 21 in the US. The lead single, "The Hearts Filthy Lesson", performed poorly but the following singles, "Strangers When We Meet" and a remix of "Hallo Spaceboy" featuring Pet Shop Boys, performed well in the UK.

Bowie supported the album through the Outside Tour, but was criticised for not playing older hits. Multiple planned sequels to Outside never came to fruition, leaving the album's story on a cliffhanger. Instead, Bowie used musical ideas from the album and tour for his next record, Earthling (1997). Retrospectively, Outside has received more positive assessments, with most continuing to praise the music but criticising the story and length. The album was reissued in 2003 and remastered in 2021 as part of the box set Brilliant Adventure (1992–2001).