Arcturus

Arcturus is a minor character in LEGO Ninjago: Masters of Spinjitzu. He was the Anacondrai General during the Serpentine Wars, and was banished to the Cursed Realm for his actions. Nevertheless his reputation was great enough that a constellation was named after him.

Spellbound
During the Serpentine War, General Arcturus led the Anacondrai to victory in taking Jamanakai Village. An alliance of Elemental Masters drove the Serpentine back, but they soon countered with the aid of Master Chen. Eventually, the alliance managed to defeat the Serpentine armies using the Sacred Flutes, sealing most of them away in underground tombs. However, Arcturus and the other Anacondrai Generals were put on trial and though they pleaded for mercy, Garmadon banished them to the Cursed Realm.

Codename: Arcturus
Decades later during the Nindroid crisis, Sensei Wu remembered facing Arcturus in battle, and Garmadon noted that a constellation had been named after him, but the two were unable to guess at the meaning behind the association of his name with the Overlord's project.

Project: Arcturus was eventually discovered to be a rocket of the same name as the Serpentine. The rocket carried the Nindroids, and the ninja into space, where the Overlord hoped to obtain the Golden Weapons.

The Corridor of Elders
The spirit of Arcturus was freed from the Cursed Realm during the second Serpentine War when Garmadon was sent there to take the General's place. Upon being freed, they discovered Chen's imposter anacondrai and cursed them instead, including Chen (who Arcturus denounced as an imposter, a cheater, and a liar). Arcturus and the other generals thanked Lloyd for brining peace between humans and Serpentine before restoring Pythor to his original size as a reward for his newfound courage.

Project: Arcturus
Project: Arcturus was a rocket that was used by the Digital Overlord, another Serpentine, and the Nindroids to retrieve what remains of the Golden Weapons. It is evident that Pythor either remembered or had heard about him, and so named the rocket after him.

Trivia

 * The Arcturus constellation may be the Ninjago equivalent of the real-life constellation Draco, usually represented as a serpent like dragon.
 * He is the only seen Anacondrai to have green eyes rather than red.