Queen mother is a title or position reserved for a widowed queen consort (a queen dowager) whose son or daughter from that marriage is the reigning monarch. The term has been used in England since at least 1577. The title arises in hereditary monarchies.

A queen consort, as wife of a king, has a royal position of great importance, but she does not normally have any rights to succeed him as monarch after his death.

The queen consort's eldest son (or daughter, if there is no son or if the kingdom practices absolute primogeniture) would normally be crowned as successor upon the king's death, often leaving the new monarch's mother still alive, but no longer holding any official position. A new king, of course, might already be married, or marry subsequently, and would have his own queen consort. A daughter who succeeded would be a queen regnant and normally called simply "the Queen," so a confusion of titles could result.