The canonical four are:
西施 (Xi Shi, Spring & Autumn period - 'sinking fish');
王昭君 (Wang Zhaojun, Western Han - 'alighting goose');
貂蝉 (Diaochan, late Han - 'moon hiding');
杨贵妃 (Yang Guifei, Tang - 'shaming flowers'). Each maps to one element of the
沉鱼落雁闭月羞花 couplet.