Ninja Five-O, known in the PAL region as Ninja Cop, is an action platform video game developed by Hudson Soft and published by Konami. It was released for the Game Boy Advance in North America and Europe in April 2003. Players take the role of Joe Osugi, a ninja who must stop a terrorist group influenced by mystical masks. It was first announced at "Konami Gamers' Day" in early 2003.

The game received generally positive reviews from video game critics, but it failed to garner sales and is often regarded as one of the most sought-after handheld games.

Ninja Five-O is an action game is centered around Joe Osugi, a ninja tasked with stopping a terrorist group influenced by the Mad Masks, masks that give the wearer obscene power. As Osugi, the player must defeat the terrorists and rescue hostages through five missions with three levels and a boss battle.