As promised, Microsoft is now offering Xbox Live Gold members a chance to change their gamertag to one of nearly 1 million old ones that are now being recycled.

Microsoft says

So, where did all these previously-unavailable Gamertags come from? These Gamertags are from the original Xbox era, the same source of Gamertags we used in our 2011 release. These accounts never migrated to Xbox 360 and as a result they have been inactive for quite some time.

Some of the gamertags that have been freed up include:

Proper Names

Pop culture references (Entertainment, sports, gaming)

Types of Food

Geography and Travel

Science and Technology

Math and Numbers

Animals

Some of the greatest inventions of all time

Xbox Live Gold subscribers with active subscriptions and at least 1 year of cumulative Xbox Live Gold access can change their gamertag at Xbox.com. They can also change them via the Xbox Windows 10 app or on the Xbox One console.

Change your gamertag at Xbox.com