Its MacOS. On An Unmodified Wii!
How has this seemingly impossible task been achieved? Seasoned Mac enthusiasts will remember the days when Apple machines used PowerPC processors, and the Wii uses a PowerPC chip thats a close cousin of those used in the Mac G3 series of computers. Since the Wii can run a Linux-based OS, it can therefore run Mac-on-Linux, providing in theory an environment in which it can host one of the PowerPC versions of MacOS.
Source: Its MacOS. On An Unmodified Wii!
Huh, look at that