Windows Server

Windows Server is a family of server operating systems by Microsoft. While Windows NT 3.1 to 2000 had server editions, Windows Server 2003 would be the first to be released under a separate brand name from its client counterpart.

Windows Server 2003 and 2003 R2
Windows Server 2003 is a server operating system released by Microsoft in 2003. It is considered the server counterpart of Windows XP, although it introduces additional kernel improvements. It does not have a default wallpaper, although it does have a branding wallpaper, which is similar to XP's but features a grey background and uses the Server 2003 wordmark instead. Microsoft would release a slightly updated version titled Windows Server 2003 R2 in 2005. The branding wallpaper is identical save for the logo being changed to reflect it being R2. The rest set of wallpapers are the same as Windows XP.

Windows Home Server
Windows Home Server is a home-oriented version of Server 2003 released in 2007. It features a completely different branding wallpaper that resembles the aurora design present in areas of Windows Vista; unlike in Server 2003, this is set as the default wallpaper. As it was released after Vista, the Windows logo is the newer one used from 2006 to 2011, while the wordmark is in Segoe UI. According to Charlie Kindel, Kýnan Antos "drew all the assets", meaning he would have designed the wallpaper as well as other graphics used in Home Server.

Desktop wallpaper
Windows Server 2008 is a server operating system released by Microsoft in 2008. It is the server counterpart of Windows Vista. Like Server 2003 and earlier versions, it does not have a default wallpaper, although it features a grey aurora branding wallpaper designed by Frank Bisono titled server. Oddly it is at 800x600, unlike Vista's 1920x1440/1920x1200 wallpapers. The wordmark and logo is placed in roughly the same spot as 2003's wallpaper.

Logon background
The logon background is simply, the same background color as Windows Vista Starter.

Setup backgrounds
Both the preinstallation environment and the installation process uses the same background as Windows Vista Service Pack 1 and Service Pack 2 but grayscaled. The background used for the initial setup window is based on a portion of the desktop background but darker.

Desktop wallpaper
Windows Server 2008 R2 is a server operating system released by Microsoft in 2009. It is the server counterpart of Windows 7. Its branding wallpaper is similar to that of Server 2008, although this time it is widescreen and the logo is smaller. Microsoft would go on to release Windows Home Server 2011 in 2011, a home-oriented version. While it features a different background color, the branding wallpaper is identical to Server 2008 R2's.

Logon background
The logon background is similar to the branding desktop wallpaper but darker.

Setup backgrounds
The background in the initial setup window remains the same as Windows Server 2008. In Windows Server 2008 R2, it's also used for both the preinstallation environment and the installation process.

Desktop wallpaper
Windows Server 2012 is a server operating system released by Microsoft in 2012. It is the server counterpart of Windows 8. It features a very minimalistic branding wallpaper, which is simply dark grey with a small white Server 2012 logo and wordmark on the bottom right corner. It is the first server version since Home Server to have the branding wallpaper set as the default wallpaper. The following year, Microsoft released Windows Server 2012 R2, the server counterpart of Windows 8.1. Its branding wallpaper is very similar, except featuring an even darker gray and the wordmark reflects it being Server 2012 R2.

Lock screen wallpaper
The default lock screen wallpaper is same as the default desktop wallpaper albeit without a logo and wordmark. The background itself consists of simply

Windows Server 2016 and 2019
Windows Server 2016 is a server operating system released by Microsoft in 2016. It is the server counterpart of Windows 10. It features the same default wallpaper as 10 versions 1507 to 1809. Two years later, Microsoft released Windows Server 2019, featuring the same wallpaper. Windows Server 2016 is the first server version since Server 2003 to include the same set of wallpapers as the client counterpart.

Windows Server 2022
Windows Server 2022, while still in development, features the same default wallpaper as Windows 10 versions 1903-present. The rest set of desktop and lock screen wallpapers are the same as Windows 10.