Platform: Apple TV (4th generation) / Apple TV 4K
Introduction and announcement; not a sales date.
Apple source ↗Apple previewed tvOS 12 on June 4, 2018, announcing a free autumn update for Apple TV 4K and the fourth-generation model. Its security document dates release to September 17. June's preview is not final availability.

Apple · tvOS 12 preview · 2018-06-04 · Apple · tvOS 12 security content
Dolby Atmos was new for Apple TV 4K, not a capability added to the older model because it shared the system. The space screensavers were announced with footage filmed by NASA astronauts aboard the International Space Station, with location information and view switching. This entry uses original typographic cards, not frames from those videos.
Apple · tvOS 12 preview · 2018-06-04
The announcement also described password AutoFill from iPhone or iPad and Apple TV Remote in Control Center. Zero sign-on was planned with Charter later that year, depending on a supported network, provider and subscription. That plan is not presented as a verified worldwide launch-day rollout.
Apple · tvOS 12 preview · 2018-06-04
On May 13, 2019, Apple released the new Apple TV app through tvOS 12.3, with paid subscription channels and availability varying by country. The same announcement still scheduled Apple TV+ for autumn. The app, channels and original-programming service are different products, not simultaneous launches.
Apple · Apple TV app · 2019-05-13 · Apple · Security updates archive · 2018-2019
Selected releases, not a complete history. Dates follow Apple's release records, not the latest page edit. No builds are included.
ISO date: year-month-day.
Platform: Apple TV (4th generation) / Apple TV 4K
Introduction and announcement; not a sales date.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Release date recorded by Apple, not the document revision date.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Software update released according to Apple archive.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Software update released according to Apple archive.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Software update released according to Apple archive.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Software update released according to Apple archive.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Software update released according to Apple archive.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Software update released according to Apple archive.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Software update released according to Apple archive.
Apple source ↗Platform: Apple TV (4th generation) / Apple TV 4K
Software update released according to Apple archive.
Apple source ↗