Ryu

Grandpa Ryu (リュウ爺, Ryu-ji; Literally meaning "Grandfather Dragon") is the name of the Sennenryu that traveled with the Straw Hat Pirates (along with Apis) during the Warship Island Arc.

Ryuji was a very old and weakened dragon; so much so that he could no longer fly. Nevertheless, Apis and Luffy managed to protect him from Nelson Royale and Eric long enough to return to him to his homeland, the Lost Island, where he could be reborn. At one point, Erik had Apis hostage, and after Apis bit Erik in attempt to escape, Erik threw her off, injuring her. This made Ryuji finally get up, and roared to the sky, and flew towards Nelson, however, Ryuji was met by heavy fire, and collapsed onto the ocean surface. At the time of his death, he told Luffy that he had fulfilled his "wish". For some strange reason, Luffy was able to understand what Ryuji was saying and relayed his last message to Apis. He was sometimes somewhat senile and tried to eat both Luffy and Usopp thinking they were food.