The Microsoft Ninja Cat is a popular fan meme and unofficial mascot for Microsoft, especially Windows, featuring a cat dressed as a ninja, riding fantastical creatures like a unicorn or T-Rex, symbolizing fun, power, and the adventurous spirit of tech enthusiasts. It started as an internal sticker for Microsoft employees and exploded in popularity online, leading to custom wallpapers, merchandise, and even exclusive Windows emojis, becoming a beloved icon for Microsoft fans.