The Japanese company Nintendo released a product world-wide in the late 1990s called "Game Boy Color". But in the UK, and elsewhere, "Color" is spelled "Colour".
For a long time, I've been trying to figure out whether they really released it as "Game Boy Color" even in the UK. It seems unlikely, since it would be seen as a typo, but on the other hand, it origins from Japan and that was the original "product name"… So I'm torn between theories.
I've read the Wikipedia article which didn't seem to mention anything about this.
Best Answer
Both the official Nintendo UK page at https://www.nintendo.co.uk/Corporate/Nintendo-History/Game-Boy-Color/Game-Boy-Color-627137.html and what seems to be the official Nintendo-supplied Amazon UK shop page for the device at https://www.amazon.co.uk/Nintendo-GameBoy-Color-Purple-Console/dp/B00000J97G refer to it using the American English Color. So it appears that the product is referred to as the Game Boy Color everywhere in the English speaking world.
This makes sense: the word "Color" in the name isn't used in the context of the dictionary word that means "the shade of visible light an object is reflecting", but rather as an integral part of the brand name used to differentiate it from the original Game Boy released before that. And while it does happen that a product is rebranded for different markets, this generally only happens in case there is a trademark dispute in a specific region or if a name has an unfortunate meaning that can negatively impact sales.