There have been nine users of One for all, an extremely powerful quirk that has the rare ability to be transferred. With it's current holder being Izuku Midoriya.
The Quirk began around the point when a man by the name of All For One who had a quirk that could steal others and also give them away. He forcefully gave his younger brother a quirk that allowed him to stockpile power within his body. However, unknown to them, the little brother already had a Quirk with no effect other than that it could be transferred to others. His Quirk and the Quirk his brother gave him merged to become One For All. He tried to defeat his brother but failed.
At some point in his life he transferred his Quirk to another person hoping that a future user would use it to defeat his brother.
For 7 generations each user had failed to defeat All For One however with each passing on the Quirk became stronger and stronger with each generation until reached it's 8th Holder Toshinori Yagi who used it to defeat All For One however knowing that a great evil will rise again to take his place, he passed it to the 9th and current Holder Izuku Midoriya.
Upon the death of a previous Holder of One For All, A fraction of their consciousnesses appears and lingers in the Quirk. One For All has some kind of subconscious realm where these fractions exist. The realm seems to have some connection to One For All's counterpart Quirk, All For One. It is later revealed that this is due to the fact that Quirks are engraved with the consciousnesses of their users, so any new user who receives One For All has their conscious embedded and placed into the subconscious realm even if the previous user has died,As shown with the 7th user.
One For All is transferrable by current a holder, The method of inheritance and transference of One For All is done by the recipient ingesting the current wielder's DNA, as shown when All Might gave Izuku Midoriya a strand of his hair to ingest, which let the latter inherit One For All. The Quirk can not be stolen as requires the will of the owner to pass on however this does not mean One For All cannot be forcibly passed on.
The previous owner can still access remnants of embers of this power and thus still access its power. However, these leftover embers will not last for long, and the previous One For All will slowly lose their access over the Quirk, resulting in the predecessor losing One For All completely.
- Yoichi Shigaraki(1st Holder)
- 2 Unnamed Holders
- Hikage Shinomori(4th Holder)
- Daigoro Banjo(5th Holder)
- En(6th Holder)
- Nana Shimura(7th Holder)
- Toshinori Yagi(8th Holder)
- Izuku Midoriya(9th and Current Holder)
One For All has been bestowed to nine different hosts in total, starting with Yoichi Shigaraki, the younger brother of All For One. Alongside the Quirk, its origins and the story between the two brothers have been passed on.
Because One For All can only be transferred willingly, its presumed that each wielder had some form of personal connection with at least their corresponding predecessor and successor. Every host was entrusted, not only with the Quirk but also with the duty of using it to stop the evil of All For One.
Most holders of One For All have been consider among the strongest Heroes of their generation. All members except Izuku had fought with All For One though none had been able to defeat him until Toshinori Yagi.
- Out of all Holders, En is the only holder of One For All whose name doesn't have a kanji in conjuction to what number user they are.