Brook is the musician on the Thousand Sunny. He is one of the few characters from One Piece who are immortal. However, even the skeleton can be destroyed in a certain way.
Why is Brook immortal? The Straw Hat Pirate ate the Revive-Revive Fruit. With his death, his Devil Fruit power activated and his soul returned from the afterlife.
Unfortunately, Brook died in the misty, mysterious triangle, which is why his soul searched for a whole year for its body. During this time, his body was just a skeleton, which is why he now lives on as a skeleton man.
Brook no longer ages and can therefore live forever. Even if his bones break or are separated, Brook can regenerate. Milk helps him to regenerate his bones.
Thus, Brook is one of the 6 immortal characters known in One Piece so far. Besides him, 4 of the Five Elders and Imu have eternal life, meaning individuals in the World Government.
However, although the Straw Hat Pirate is technically immortal, he reveals a method by which he can be destroyed. This distinguishes him from the 5 other characters who are truly immortal in One Piece, namely Imu and four of the Five Elders.
Brook can be defeated by a method
How can he still be destroyed? Brook reveals in a fight against a fishman that takes place in chapter 643 of the manga that there is a method to defeat him. To prevent the skeleton man from regenerating his body, his bones must be completely shattered.
To what extent the bones need to be mangled is left open. After all, with milk, it is possible for him to heal minor fractures in the skeleton. An explosion or something similar would likely mean Brook’s ultimate death, as the fruit can only resurrect once.
Big Mom would also be a candidate to kill the Straw Hat Pirate. She can extract a person’s soul with her Soul Fruit. This would sever Brook’s soul from his body and he would die regardless. However, whether her powers even have an effect on the skeleton man was never seen in the anime or manga.
In addition to Brook, there are other characters in the World Government who are immortal. They owe this to Trafalgar Law’s Devil Fruit, which can grant eternal life. And exactly for that reason, the pirate has to fear: A character from One Piece must fight for his life for the 2nd time in the grand finale
