The Green Dragon is an ancient Japanese dragon that guarded the Sword of Fate, which could defeat the Black Samurai.
Physical appearance[]

The Green Dragon in his youth
The Green Dragon has a long serpent-like body, and as his name suggests, has green scales, with dark green eyebrows and maroon around his yellow eyes, and graying fur and whiskers, which were dark green in his youth.
Personality[]
He is kind, humble, and wise as he helped Scooby-Doo and Shaggy Rogers save the day. He had no intention of evil, unlike most dragons, and battled against it instead, defeating the Black Samurai and locking him inside the Sword of Fate. He had shown to be just slightly aggressive, fighting ruthlessly against the black samurai but also questioning who is present inside of his cave (in this case Shaggy and Scooby), although still having no real intention to harm.
History[]
Early life[]
He was given the Sword of Fate by Masamune. He fought and defeated the black samurai, imprisoning the villain in his own sword, the Sword of Doom. After hiding the sword, he rested possibly to sleep in his cave for many years.
Scooby-Doo! and the Samurai Sword[]
He aided Shaggy and Scooby. When they met him in his cave, the dragon gave a brief explanation of the story, the two told him that they need his help as the Black Samurai has returned. He claimed that dragons aren't for their timeline, even though they insisted that he couldn't fear a sword he already fought with. The latter took a closer look at them and when claimed that they don't seem like samurai, he gave them the clothes needed. Opened the light of his wise ball and gave the Sword of Fate to the two. Then he took with him leaving the volcano flying.
When they met up with the Black Samurai, the green dragon said to the two that they should take the sword out so he could get into it and lead it from the inside. And it was so. He assisted them into defeating the black samurai, destroying the Sword of Doom and freeing the samurai from his curse.
Trivia[]
- After the dragon gets in the sword of fate, we don't see him get out of it. Presumably he got out of it and returned to his cave, but we just haven't seen that.