The Ninja is a large tower CPU cooler from Scythe. Featuring 6 large copper heatpipes with aluminum fins, the Ninja is a popular enthusiast air cooling heatsink/fan combination used by overclockers and silent pc enthusiasts due to it's high efficiency with little to no airflow. The Ninja is packaged with a medium speed 120mm Scythe fan, which is quite good in terms of cooling power as well as noise levels when controlled via motherboard or dedicated fan control unit. While quite heavy, most of the weight is concentraited in the base of the heatsink, allowing for a computer case that can be moved without worry. Similarly, it's large size makes for awkward or impossible placement on many motherboards, often blocking one or two of the closely placed DIMM slots.
Today the Scythe Ninja has become almost a legend in it's field, spawning other versions, such as the half-tower mini-Ninja (Minja), the all copper Ninja, and more recently the Ninja 2, as well as copy-cat designs such as the OCZ Vindicator.