貴様
Kisama
きさま
Originally an honorific meaning something like 'your esteemed self,' but over centuries its meaning completely flipped. Today it carries strong contempt and hostility — used almost exclusively by villains and samurai characters in anime, manga, and period dramas. If a foreigner uses this in real life after picking it up from anime, things will go very badly.
Examples
アニメで「貴様」ってよく聞くけど、実際に使ったらやばいよ
You hear "kisama" a lot in anime, but if you actually used it in real life, it would not go well.
Advising a friend who is studying Japanese
貴様って本来は丁寧語だったらしいよ
Apparently "kisama" was originally a polite word.
Sharing Japanese language trivia
ゲームのボスキャラ「貴様、ここまで来るとはな」
Game boss character: "Kisama... you dare come this far."
「貴様」は日常で使ったら喧嘩になるからね
If you use "kisama" in real life, you will start a fight.