It HAS TO BE SLAVE KNIGHT GAEL FROM DARK SOULS 3 HE WAS PERFECT THE ARENA THE MUSIC HIS MOVE SET THE BUILD UP AND ITS THE PERFECT ENDING FOR THE TRILOGY THAT SHOWS THAT NOT THE GODS WILL BE AT THE END OF TIME AND IT SHOWS THAT EVERYTHING IN ALL SOULS GAMES LED TO THIS FIGHTING THE REASON WHY WHE EXIST AND NOBODY CAN NAME A BETTER BOSS THEN SLAVE KNIGHT GAEL!
Sin from FFX was hard core.
Returns every 10 years after someone kills themselves to kill it, and never allows society to get beyond a weird magic-bronze-age because it squashes big cities better than Godzilla does.