Ninjago (previously known as Ninjago: Masters of Spinjitzu until 2019) is an animated epic-fantasy superhero television series produced by The Lego Group. It was created to coincide with the Lego Ninjago line of construction toys, which is based on the characters and events of the series. It centers on the fictional world of Ninjago, telling the story of a group of six teenage ninja and their battles against the forces of evil. The series was created by Michael Hegner and Tommy Andreasen, two Danish film producers. The storyline was written by Kevin and Dan Hageman until the ninth season; their successor as the head writer was Bragi Schut. The series features the voices of Jillian Michaels, Sam Vincent, Vincent Tong, Brent Miller, Michael Adamthwaite, Kirby Morrow, Andrew Francis, Paul Dobson, Kelly Metzger, and Mark Oliver. The voice cast was recorded in Canada for its entire run. The music was scored by composers Michael Kramer and Jay Vincent.

The series was in continuous production for over a decade and celebrated its tenth anniversary on January 14, 2021. It began with two pilot episodes in January 2011, which were followed by two 13-episode seasons that aired from December 2011 to November 2012. Both the Lego theme and the series had an intended shelf life of three years with the second season planned as the original ending. However, the success of the series and its product line led to the show continuing production, with thirteen more seasons, a special, a feature film adaptation, and a four-episode miniseries being released. Ninjago: Masters of Spinjitzu was produced in Copenhagen, Denmark, by Wil Film ApS for its first ten seasons. The production was relocated to WildBrain Studios in Canada for the eleventh season, and the series was retitled Ninjago. The series concluded on October 1, 2022, with the second part of the fifteenth season being released on Netflix in Australia and New Zealand.

In Denmark, where the series' original production companies are located, it premiered on Cartoon Network. It aired on various Cartoon Network feeds internationally. In the United States, it aired on Cartoon Network until 2020, when premieres moved to Netflix. In Canada, the series was broadcast on Teletoon and YTV.

A sequel series titled Ninjago: Dragons Rising, set in the same continuity, debuted on June 1, 2023.