| The Butterfly Effect | |
| Type: | studio |
| Artist: | Moonspell |
| Cover: | MoonspellBFX.jpg |
| Released: | 13 September 1999 |
| Recorded: | June 1999 |
| Studio: | Trident Studios, London |
| Label: | Century Media |
| Producer: | Andy Reilly |
| Prev Title: | Sin/Pecado |
| Prev Year: | 1998 |
| Next Title: | Darkness and Hope |
| Next Year: | 2001 |
The Butterfly Effect is the fourth studio album by Portuguese gothic metal band Moonspell, released in 1999, inspired by chaos theory. The album is characterised by a more experimental approach than their previous material, incorporating many elements of electronic music and industrial metal. The music is composed primarily by the band's keyboardist, Pedro Paixão. "Tired" samples Mozart's Requiem.