王太后，是王、亲王、国王之母的封号。最早在中国战国时期就有王太后出现，是世界上最早的太后。

中国最早在战国时期，就已经有王太后存在，如赵国的赵威后、秦国的宣太后、夏太后等等，都是王的母亲，因而得称王太后。

汉朝延续了战国时期王母称王太后的制度，后宫妃嫔若生子、且其子有封国，可在皇帝崩后出宫前往其子的封国，成为该国的王太后，又称王国太后，如代太后薄姬、中山太后冯媛等等。汉武帝时，齐王刘闳之母王夫人深受宠爱。王夫人死后，武帝赐她为“齐王太后”。

东汉以后，王母降称王太妃，或称王国太妃，如唐朝赵国太妃杨氏，而王太后一号在中国自汉朝以后，仅于部分君主只称王的政权所使用，如五胡十六国的前凉，张重华登基以后，生母马氏、嫡母严氏并尊为王太后，同时为有所区别，生母马氏称王太后、嫡母严氏称大王太后。

A queen dowager, dowager queen or queen mother (compare: princess dowager, dowager princess or princess mother) is a title or status generally held by the widow of a king. In the case of the widow of an emperor, the title of empress dowager is used. Its full meaning is clear from the two words from which it is composed: queen indicates someone who served as queen consort (i.e. wife of a king), while dowager indicates a woman who holds the title from her deceased husband. (A queen who rules in her own right and not due to marriage to a king is a queen regnant.)