Fly by Night or Fly-by-Night may refer to:
Film and television
Fly-by-Night (film), a 1942 American thriller
Fly by Night (TV play), a 1962 Australian TV play
Fly by Night, a 1992 film directed by Steve Gomer
Fly by Night (film), a 2019 Malaysian crime thriller
Fly by Night (TV series), a 1991 Canadian adventure series starring David James Elliott "Fly by Night" (Mighty Max), an episode of the television series Mighty Max
Fiction
Fly by Night (Hardinge novel), a 2005 children's novel by Frances Hardinge
Fly-by-Night (Peyton novel), a 1968 children's novel by K. M. Peyton
"Fly-by-Night", a short story by Larry Niven included in the Man-Kzin Wars collections "Fly-by-Night", a mysterious flower in the Japanese animated film Mary and the Witch's Flower
Music
Fly by Night (album), a 1975 album by Rush
"Fly by Night" (Rush song), 1975
"Fly by Night" (Andy Williams song), 1961
"Fly by Night", a song by Ian Anderson from Walk into Light
"Fly by Night", a song by Matt Bianco from Matt Bianco
Fly by Night (musical), a musical written by Will Connolly, Michael Mitnick, and Kim Rosenstock