Which version of macOS was the last to use the "OS X" branding?
Answer
OS X El Capitan (10.11)
OS X El Capitan, version 10.11, was the last macOS release to use the “OS X” branding.
El Capitan was released on September 30, 2015, following OS X Yosemite. Apple renamed the platform to macOS in 2016, when macOS Sierra 10.12 replaced El Capitan. As a result, El Capitan is the final operating system whose official release name began with “OS X.”
The name “El Capitan” refers to the granite rock formation in Yosemite National Park. Continuing Apple’s California naming scheme, the release emphasized performance, stability, and refinement rather than a dramatic visual redesign. It introduced features including Split View, improvements to Mission Control, and a more capable Notes app.
The branding change did not represent a completely new operating system. macOS Sierra remained part of the same platform lineage, but its name aligned Apple’s desktop software with iOS, watchOS, and tvOS. El Capitan is therefore the correct answer for branding history, not for the final version that supported every older Mac model.