Ronin is the main antagonist of the non-canon 2015 video-game LEGO Ninjago: Shadow of Ronin, and a major character in the canon TV series LEGO Ninjago: Masters of Spinjitzu, serving as a major anti-hero in Season 5: Possession, as a supporting anti-hero in Season 6: Skybound, as a supporting character in the TV special Day of the Departed, as a minor character in both Season 7: The Hands of Time and Season 9: Hunted, and as a cameo character in Season 10: March of the Oni. He later returns as the main antagonist of The Island.
He is a selfish, yet skilled and intelligent mercenary based in Stiix with his airship R.E.X. He is often hired by Master Chen for important tasks such as capturing Zane and releasing the banished master from the Cursed Realm.
Up until the destruction of the Obsidian Glaive, Ronin was a memory thief known to remove people's memories and replace them with lies about their past.
He was voiced by Brian Dobson, who also voiced Soul Archer in the same series itself.