When will my device get the Android 6.0 update (Marshmallow)? Android "M" was officially announced on at the Google I/O conference on May 28, 2015 and revealed to be 6.0 Marshmallow on August 17, 2015.

You can review the high-level changes at the Android website and the announcement on the official Android blog.

Of course, not all devices will get this update right away and others won't get it at all. Each manufacturer and carrier often choose to add their custom modifications which tend to delay the official release.

When will each device get Android 6.0, either officially or unofficially, if ever?

See also:


When will my device get the Android 5.1 update (Lollipop)?
When will my device get the Android 7.0 update (Nougat)?
This community wiki will list all of the known and rumored dates for devices. If you have an update make sure to follow the format that's been established, and the following guidelines:


Keep devices in alphabetical order listing the manufacturer and model
Specify if the date is confirmed or rumored and link to the source
If there is an unofficial release, link to the site where it can be downloaded


Phones

HTC


Butterfly 3 - announced - (source)
Desire 816 - announced - (source)
Desire 820 - announced - (source)
Desire 826 - announced - (source)
One E8 - announced - (source)
One E9 - announced - (source)
One E9+ - announced - (source)
One M7: Never (confirmed)
One M8 - by the end of 2015 - (source)
One M8 EYE - announced - (source)
One M9 - by the end of 2015 - (source)
One M9+ - announced - (source)
One ME - announced - (source)


LG


Nexus 4: Never (confirmed)
Nexus 5: 2015-10-05 (confirmed)


Motorola


DROID Turbo - announced - (source)
Moto G and Moto G with 4G LTE (2nd generation) - announced - (source)
Moto G (3rd generation) - announced - (source)
Moto MAXX - announced - (source)
2014 Moto Turbo - announced - (source)
Moto X (2nd generation) - announced - (source)


Pure Edition in the US
in Latin America, Europe and Asia

Moto X (3rd generation) - announced - (source)


Pure Edition
Style
Play

Nexus 6: 2015-10-05 (confirmed)


OnePlus


OnePlus One


Cyanogen OS - in first quarter of 2016 - (Source)
OxygenOS - no fixed date confirmed, but not in 2015 - (Source)

OnePlus Two - in first quarter of 2016 - (Source)


Tablets

Asus


Nexus 7 (2012): Never (confirmed)
Nexus 7 (2013) - 2015-10-05 (confirmed)


HTC


Nexus 9: 2015-10-05 (confirmed)


Samsung


Nexus 10: Never (confirmed)


Other


Nexus Player: 2015-10-05 (confirmed)