''Delerium'' is a [[UsefulNotes/{{Canada}} Canadian]] musical group created by Bill Leeb in 1987, as a side project of his influential industrial music act: Music/FrontLineAssembly. The band's musical style has a broad range, from dark {{industrial}} soundscapes and {{ambient}} music, to [[ElectronicMusic electronic pop]] and {{trance}} hits. They are best known for their 1999 worldwide hit "Silence," which features vocals from Music/SarahMcLachlan. The Tiësto remix of "Silence" has been hailed as one of the greatest trance songs of all time, over a decade after its initial release.

The band started as a duo between Leeb and fellow ''Front Line Assembly'' member Michael Balch. Their debut: ''Faces, Forms & Illusions,'' contained sample-heavy collages of industrial and dark ambient music akin to Music/SkinnyPuppy and ''Front Line Assembly,'' of which Leeb and ''Faces'' collaborator Rhys Fulber were members. Fulber took over for Balch in time for ''Delerium'''s second album: ''Morpheus'' - a position he has held until the present, barring a brief absence that resulted in the 2000 album ''Poem,'' made instead by Leeb with Chris Peterson (also a ''Front Line Assembly'' alum).

Delerium's early work is considered pioneering in the field of dark ambient music. Over time, ambiance took prominence over industrial noise and voice samples from films, culminating in ''Spheres'' and ''Spheres II'' in 1994, which focused squarely on ambient music and dub techno. Sandwiched in between these albums was ''Semantic Spaces,'' the first album to feature a singer (Kirsty Thirsk, who would be credited as "The Voice of Delerium") and a sharp swerve into the realm of world beat and ethnic electronica. ''Delerium'''s output since 1994 has grown ever poppier, receiving comparisons to the works of ''Deep Forest,'' ''Future Sound of London,'' and Music/{{Enigma}} (''Semantic Spaces'' even uses [[FollowTheLeader many of the same samples Deep Forest's debut did.]]) ''Delerium'' have scored a few decent radio hits since the 1997 release of ''Karma,'' with "Aria," "After All," and "Innocente (Falling in Love)" still in rotation on some pop stations.

Aside from Thirsk, ''Delerium'' features a long list of female vocalists, including Sarah [=Mc=]Lachlan, Leigh Nash (of Music/SixpenceNoneTheRicher), Elsieanne Caplette (of ''Elsiane''), Lisa Gerrard (sampled only), Jaël (of Swiss band ''Lunik''), Camille Henderson, Nerina Pallot, Emily Haines (of Music/{{Metric}}), Jacqui Hunt (of ''Single Gun Theory''), Isabel Bayrakdarian, Shelley Harland, and Mediæval Bæbes. Male featured vocalists include Matthew Sweet, Greg Froese, Michael Logen, and Leeb himself.

Although it may be argued that ''Front Line Assembly'' has the largest cult following of all of Leeb and associates' projects, ''Delerium'' is undoubtedly the most financially successful. In addition to these two mainstays, Leeb, Fulber, Peterson, and Balch have all created a variety of similarly veined projects such as ''Conjure One,'' ''Fauxliage'' (basically Delerium fronted by Leigh Nash), ''Equinox,'' ''Intermix,'' ''Noise Unit,'' ''Pro-Tech,'' and ''Synæsthesia.''

!! Discography:

* ''Faces, Forms & Illusions'' (1989)
* ''Morpheus'' (1989)
* ''Syrophenikan'' (1990)
* ''Stone Tower'' (1991)
* ''Euphoric'' (1991, EP)
* ''Spiritual Archives'' (1991)
* ''Spheres'' (1994)
* ''Spheres 2'' (1994)
* ''Semantic Spaces'' (1994)
* ''Karma'' (1997)
* ''Poem'' (2000)
* ''Chimera'' (2003)
* ''Nuages du Monde'' (2006)
* ''Voice (An Acoustic Collection)'' (2010)
* ''Music Box Opera'' (2012)
* ''Mythologie'' (2016)

!! Tropes that apply to ''Delerium:''

* AfterTheEnd: The music video for the track "Angelicus" as it is revealed bit by bit as the video goes along. The orphans seen in the video are what's left of Humankind.
* CherubicChoir: When they're not sampling them, ''Delerium'' does make use of them.
* IAmTheBand: For most of their career, ''Delerium'' was comprised of Bill Leeb and Rhys Fulber. After Fulber left in 2000 to create ''Conjure One,'' Leeb remained the sole member of ''Delerium,'' until Fulber's return in 2003.
* OminousLatinChanting: Very prominent in their earlier works, including a rather stereotypical usage of the trope on ''Spheres.''
* OneWomanWail: Used on ''Semantic Spaces'' due a few songs incorporating a wordless vocal track. Averted elsewhere: Despite the prominence of female vocalists throughout their more recent albums, no album has been saturated with this trope since.
* RuleOfSymbolism / ShoutOut: The works of ''Delerium'' are infused with this, as well as the many side projects of Bill Leeb and Rhys Fulber.
** Many of the track names on any given ''Delerium'' album and any album of the related side-projects by Bill Leeb and/or Rhys Fulber are symbolically tied into the track itself, or a thematic shout out related to the track.
** ''Spheres'' and ''Spheres II'' featured prominent sampling of NASA missions, as well as dialogue and score from ''Film/TwoThousandOneASpaceOdyssey.''
* {{Sampling}}: A very common mainstay in the works of ''Delerium,'' especially due to their roots in vocal less industrial dance music. Early period sampling mainly came from films and documentaries; mid-and-late period ''Delerium'' focused on sci-fi films, and obscure Middle Eastern and European folk songs.
* SmallNameBigEgo: Averted big time with Bill Leeb and Rhys Fulber. Despite their popularity and their success, both men have remained very humble and private. Fulber is one of the most sought after producers in the music industry and has gone onto producing and working on countless albums. Leeb has contributed to various other projects, and provided the soundtracks for the video games ''VideoGame/QuakeIIIArena'' (as a part of Sonic Mayhem) and ''VideoGame/AirMech.''
* UrbanFantasy: The music videos for the tracks "Dust in Gravity" and "Monarch."