Ending 1: The Story ends with Luffy dying the same way as Roger, announcing the new age of Piracy, restarting the Loop, and not changing anything.

Ending 2: One Piece turns out to be ‘The Friends we make along the Way’ and nothing else.

Ending 3: Blackbeard wins and starts the Age of Darkness and becomes the Ruler of The World.

Ending 4: It turns out Luffy and Joy Boy were the exact same person; Luffy goes back in time and becomes Joy Boy.

Ending 5: The Story ends with Brook retelling the story of Straw Hat Pirates in front of their Grave or a bunch of children since he’s the only one left alive.

Ending 6: Luffy was, in fact, Joy Boy’s reincarnation and nothing else. He won because of Destiny and not because of his own sweat and hard work.

Ending 7: Law uses Immortality Operation on Luffy, causing him to live longer than everyone else. He sees his crew eventually dying of old age while he’s the only one left.

Ending 8: Instead of siding with his family in the final war, Garp sides with the Marine and becomes the Villain of The World.

Ending 9: Shanks is one of the final villains, and Luffy has to defeat him.

Ending 10: Luffy marries whoever and has a son named Buffy who will have his own Anime, called ‘Two Pieces: The Next Pirate Generation’

Src: opfanpage.com