Which company published the Xbox 360 version of Guitar Hero II?

Which company published the Xbox 360 version of Guitar Hero II? The answer is Activision.

Guitar Hero II was developed by Harmonix, but its publisher depended on the platform. RedOctane published the PlayStation 2 version, while Activision published the Xbox 360 version released in 2007. Therefore, Activision is the canonical answer when the question specifies Xbox 360.

The Xbox 360 edition was more than a direct port. It added 10 exclusive songs, downloadable content through Xbox Live Marketplace, improved graphics, online leaderboards, and a reorganized song progression. It was bundled with a white Gibson Explorer-style guitar controller rather than the red Gibson SG associated with the PlayStation 2 release.

The publisher change reflects the business history of the series: Activision acquired RedOctane in 2006 and became the major publishing force behind later Guitar Hero releases. Harmonix remained important as the developer of Guitar Hero II, but developer and publisher are different roles. Confusing Harmonix or RedOctane with Activision is the main trap in this question.