Lego Ninja

Ninja was a theme and product range of the construction toy Lego. Launched in 1998, the collection was its own theme. It had many elements of the ninja warriors from feudal Japan. The majority of the sets were released in 1998 and 1999; however, three small sets of minifigures were released in 2000 as part of the ‘Mini Heroes Collection’. After this, the theme was discontinued, and was effectively replaced by the “Knights Castle” theme in 2000.
Legacy.
In 2010, series 1 of The Collectable Minifigures Series contained a ninja minifigure clearly based on the theme. A year later, in 2011, Lego released "Ninjago: Masters of Spinjitzu", which took heavy inspiration from the Ninja theme.