| Action Software (Oscar Gallego Sendin, Ignacio Mendez, Javier Fafula) | Developer | |
| ActionMan | Developer | |
| Actioncraft | Publisher | |
| Actionsoft | DeveloperPublisher | |
| Active | Developer | |
| Active Gaming Media | DeveloperPublisher | |
| Active Magic (Davor Magdic) | Developer | |
| Active Magic (Predrag Beciric, Aleksandar Petrovic, Vojislav Mihailovic, Predrag Milicevic) | Developer | |
| Active Minds (John Pickford, Mark R. Jones, Simon Butler, David Whittaker) | Developer | |
| Active Software | DeveloperPublisher | |
| ActiveUP Games | Developer | |
| Activision | DeveloperPublisher | |
| Activision 02 | Publisher | |
| Activision Blizzard | Publisher | |
| Activision EU | Publisher | |
| Activision EU/NA | Publisher | |
| Activision NA | Publisher | |
| Activision NA/EU | Publisher | |
| Activision O2 | Publisher | |
| Activision Publishing | Publisher | |
| Activision Publishing, Inc. | DeveloperPublisher | |
| Activision Value | DeveloperPublisher | |
| Activision Value Publishing | Publisher | |
| Activision Value Publishing, Inc. | Publisher | |
| Activision ValueAU | Publisher | |
| Activision, | Publisher | |
| ActivisionAU | Publisher | |
| ActivisionEU | Publisher | |
| ActivisionEU,NA | Publisher | |
| ActivisionJP | Publisher | |
| ActivisionJP,PAL | Publisher | |
| ActivisionNA | Publisher | |
| ActivisionNA, PAL | Publisher | |
| ActivisionNA,PAL | Publisher | |
| ActivisionPAL | Publisher | |
| ActivisionPAL,NA | Publisher | |
| Activison | Developer | |
| Actoon Studio | DeveloperPublisher | |
| Actos Games | DeveloperPublisher | |
| Actoz Soft | DeveloperPublisher | |
| Acttil | DeveloperPublisher | |
| Actual Humans | Developer | |
| Actualize | Publisher | |
| Actually The Moon | Developer | |
| Actura Software | DeveloperPublisher | |
| Acumen Software | Publisher | |
| Ada Interactive | Developer | |
| Ada Rook | Developer | |
| Adafheyesh | Developer | |
| Adagio Games | Developer | |