Consoles :

Atari 2600 (1981)

Atari 5200 (1982)

Entex AdventureVision (1982)
Emerson Arcadia (1982, "Space Squadron")

Atari XEGS

Colecovision (1983)

Mattel Intellivision (1983)
Nintendo Famicon (1983 "Stargate" – Atari)

Atari 2600 (1984, "Defender II" – Atari)
Nintendo Famicon (1988 "Defender II" – Hal America)

Nintendo Game Boy (1995, "Defender / Joust")

Nintendo Super Famicom (1996, "Williams Arcade's Greatest Hits")

Sega Mega Drive1996, "Williams Arcade's Greatest Hits")

Atari Jaguar (1996, "Defender 2000")

Sega Saturn (1996, "Williams Arcade's Greatest Hits")

Sony PlayStation (1996, "Williams Arcade's Greatest Hits")

Nintendo Game Boy Color (1998, "Arcade Hits - Defender / Joust")

Nintendo 64 (2000, "Midway's Greatest Arcade Hits Volume I")

Sega Dreamcast (2000, "Midway's Greatest Arcade Hits Vol. 1")

Nintendo Game Boy Advance (2001, "Midway's Greatest Arcade Hits")

Nintendo Game Boy Advance (2002)

Sony PlayStation 2 (2003, "Midway Arcade Treasure")

Nintendo GameCube (2003, "Midway Arcade Treasure")

Microsoft XBOX (2003, "Midway Arcade Treasure")

Sony PSP (2005, "Midway Arcade Treasures - Extended Play")

Microsoft XBOX 360 (2006, "Xbox Live Arcade") [retired in 2010]
Computers :
Tandy Color Computer (1982, "Starfire")
Tandy Color Computer (1982, "Planet Invasion")
Tandy Color Computer (1982, "Offender")
Atari 800 (1982)
BBC B (1982, "Defender" – Acornsoft)
TI99/4a (1983)
Commodore C64 (1983)
PC [Booter] (1983)

Apple II (1983)
Commodore VIC-20 (1983)
BBC B (1983, "Super Defender" - Acornsoft)
Acorn Electron (1984, "Guardian" – Alligata)
Acorn Electron ("Gauntlet" – Micropower)
BBC B (1984, "Guardian" – Alligata)
BBC B ("Gauntlet" – Micropower)
Oric ("Defence Force" – Tansoft)
Sinclair ZX-Spectrum (1984, "Starblitz" – Softek Software)
Sinclair ZX-Spectrum (1984, "Defenda" – Interstella Software)
Commodore C64 (1984, "Guardian" – Alligata)
Commodore C64 (1985, "Guardian II" – Hi-tech Software)

Amstrad CPC (1985, "Defend or Die" – Alligata)

Amstrad CPC (1985, "Gauntlet" – Micropower)
Sinclair ZX-Spectrum (1986, "Defenda" – Interstella Software) : 128k version improved sound/graphics.
ZX Spectrum (1990, "Guardian II" - Hi-Tech Software Ltd 'UK')
Atari ST (1990, "Defender II" - ARC developments, Atari UK, limited)
Commodore Amiga (1990, "Defender II" - ARC developments, Atari UK, limited)

Commodore Amiga (1991, "Zeron"- Acid software)

Commodore Amiga (1994, "Defender" - Shareware)
PC [MS-DOS] (1995, "Williams Arcade Classics")
PC [MS Windows] (1996, "Williams Arcade Classics")
Sam Coupe (1998, - Persona)
PC [MS Windows, CD-ROM] (2004, "Midway Arcade Treasure")

Microtan 65
Others :
VFD handheld game (1982) released by Entex.
VFD handheld game (19??) released by Gakken : the screen is a little smaller than the Entex version.
Palm OS ("Midway Arcade Classic")
Tiger Game.Com ("Arcade Classics")