0
Kevin Moore
Kevin Moore
American keyboardist and composer
1
Fates Warning
Fates Warning
American progressive metal band
2
Mike Portnoy
Mike Portnoy
American drummer
3
Bobby Jarzombek
Bobby Jarzombek
American drummer
4
Dream Theater
Dream Theater
American progressive metal band
5
Chroma Key
Chroma Key
musical project of Kevin Moore
6
Mikael Ã…kerfeldt
Mikael Ã…kerfeldt
Swedish musician
7
Transatlantic
Transatlantic
Progressive rock supergroup
8
John Petrucci
John Petrucci
American guitarist
9
James LaBrie
James LaBrie
Canadian vocalist
10
Liquid Tension Experiment
Liquid Tension Experiment
American band
11
Prospect
Prospect
Slovenian band
12
Arch / Matheos
Arch / Matheos
American band
13
Bigelf
Bigelf
band
14
Symphony X
Symphony X
American progressive metal band
15
Ray Alder
Ray Alder
musician
16
Neal Morse
Neal Morse
American multi-instrumentalist and progressive rock composer
17
Redemption
Redemption
American progressive metal band
18
Sons of Apollo
Sons of Apollo
American band
19
Steven Wilson
Steven Wilson
English musician and songwriter
20
Distorted Harmony
Distorted Harmony
Isreaeli progressive metal band
21
Porcupine Tree
Porcupine Tree
British progressive rock band
22
Gordian Knot
Gordian Knot
American rock band
23
Charlie Dominici
Charlie Dominici
American musician
24
Jordan Rudess
Jordan Rudess
American keyboardist
25
Sky Architect
Sky Architect
26
Storm Corrosion
Storm Corrosion
band
27
Opeth
Opeth
Swedish progressive metal band
28
Katatonia
Katatonia
swedish metal band
29
Derek Sherinian
Derek Sherinian
American keyboardist
30
Tangerine Circus
Tangerine Circus
Members, past and present

OSI is an American progressive rock band, originally formed by Fates Warning guitarist Jim Matheos in 2002. Chroma Key keyboardist and vocalist Kevin Moore is the only other full-time member of the band. The collaboration may be considered a studio project, as its members and contributors write and track most of their material independently, sharing and developing tracks long-distance, only coming together at the end of the process for mixing and additional tracking. The band's name is a reference to the Office of Strategic Influence, a short-lived American government agency formed in 2001 to support the War on Terror through propaganda. The band has featured a number of guest musicians on its albums, including Sean Malone, Steven Wilson, Mikael Akerfeldt, Joey Vera and Gavin Harrison.

Matheos recruited Moore, Dream Theater's then-drummer Mike Portnoy, and Sean Malone (Fretless Bass and Chapman Stickist) to perform on what was originally planned to be a Matheos solo album. Matheos and Portnoy originally planned to produce a progressive metal album similar to Matheos' work in Fates Warning, however Moore's impact changed the music's direction and genre, incorporating electronica into the original progressive metal sound. The Band's debut album was released by InsideOut Music in 2003.

OSI was originally intended to be a one-off project, but Matheos and Moore found they both had gaps in their schedules so produced a follow-up. Free was released in 2006, with Portnoy returning to play drums as a session musician rather than a full band member, due to personal and musical differences between him and Moore. Blood was released in 2009, with Porcupine Tree drummer Gavin Harrison replacing Portnoy. The fourth album Fire Make Thunder was released in 2012 by Metal Blade Records, with Harrison once again on drums.