Your eyes are not deceiving you... I got an Apple TV 1st Gen, the only x86 based model (it uses a Pentium M as its CPU) booting Windows XP Service Pack 3! For reals!
This was possible through a small security flaw in the Apple TV's firmware and boot process... while the Apple TV looks for a boot.efi file on its boot partition and requires it to be a Mach-O binary to be able to boot, it doesn't actually care about the actual contents of the file! So by that note, you can wrap a kernel or bootloader from another OS into a Mach-O file and name it boot.efi, and the Apple TV won't care and will happily boot it! So after this little escapade of cursed computing, you know Linux is next!
More deets are in this video, along with a link to grab a premade disk image from the Internet Archive!
https://youtu.be/v2w5MmiRHUo