Apple has shipped every new version of macOS/OS X with a new default wallpaper. These wallpapers are usually based around the final name of that macOS release. While macOS Mojave and Catalina ship with high-resolution wallpapers that can be used on a 5K display, wallpapers in older Mac releases are of relatively low resolution meaning even if you get your hands on them, you cannot use them.
Designer @forgottentowel and the folks over at 512Pixels have collected all the default macOS wallpapers starting right from OS X 10.0 Cheetah. All the wallpapers have been upscaled to 5K meaning you can use them on almost any monitor out there without any quality issues. Do note that the 5K resolution is slightly lower than the Pro Display XDR’s 6K resolution. While you will be able to use these wallpapers on the Pro Display XDR as well, the quality might not be up to the mark. You can also use these wallpapers on your Windows-based PC.
Apple used the same default wallpaper in OS X Cheetah and Puma. In fact, up until OS X 10.4 Tiger, the company used a slightly modified version of the same Aqua wallpaper. With OS X 10.5 Leopard, the company introduced a new default wallpaper which it slightly tweaked for OS X 10.6 Snow Leopard.
Starting with OS X 10.10 Yosemite, Apple switched to a new UI, naming scheme, and a new ‘mountain’ theme for the wallpapers. This continued up until the release of macOS 10.14 Mojave which also started the trend of Apple including multiple versions of the default wallpaper to match the system-wide Dark theme.
You can download all the default OS X/macOS Wallpapers in 5K resolution from here.