Least defeated boss in Elden Ring

The boss that has been defeated by the fewest players is Dragonlord Placidusax, a legendary enemy located in the Crumbling Farum Azula. As of 13 Dec 2022, the achievement players get for defeating this out-of-the-way optional boss is the rarest boss-battle achievement/trophy, across all platforms.

The trophy "Dragonlord Placidusax" trophy has been earned by 26.1 percent of players who completed Elden Ring on the PS4, and 26.6% of those who completed it on the PS5. The statistics for xBox and PC, which are collected differently, are 38% and 43% respectively, but the ranking doesn't change.

Placidusax is an optional boss, meaning that he doesn't have to be defeated to complete the game, which goes some of the way to explaining why so few players have hunted him down. Another major factor is how hard Placidusax is to find – many players don't defeat him not because they can't, but because they didn't know he was there.