A shield-maiden (Old Norse: skjaldmær [ˈskjɑldˌmæːr]) was a female warrior from Nordic folklore and Norse mythology.

The term skjaldmær most often shows up in legendary sagas such as Hervarar saga ok Heiðreks. However, female warriors are also mentioned in the Latin work Gesta Danorum. Both the legendary sagas and Gesta Danorum were written after the Viking Age and are considered fictional. Earlier reports of fighting women occur in some Roman sources from late antiquity. They are often associated with the mythical Valkyries, which may have inspired the shield-maidens. They may have also been inspired by accounts of Amazons.

The term "shield-maiden" is a calque of skjaldmær. Since Old Norse has no word that directly translates to warrior, but rather drengr, rekkr, and seggr can all refer to male warriors, and bragnar can mean warriors, it is problematic to say that the term meant female warrior to Old Norse speakers. Judith Jesch researched the word in an attempt to find its origin. While she found that it was used to describe Amazons as well as women warriors in the sagas, typically from the East, she found no conclusive evidence that it dates to the Viking Age, and suggests that it may have entered Old Norse in the 13th century. Additionally, the term is found in the name of a ship and the nickname of a poet.

In modern English, it can refer to a generic female warrior, but is also used to refer specifically to a type of character that appears in legendary sagas. Confusingly, it is sometimes used to refer to hypothetical female warriors in the Viking Age. Jesch argues against this usage in academic works to avoid confusion between textual and literal shield-maidens. The term is also used in modern English as a synonym for 'valkyrie'. Indeed, Brynhildr, a valkyrie, describes herself as a shield-maiden in the Vǫlsunga saga. However, the text was composed in the 13th century, and not in the Viking Age. In the Viking Age, valkyries served drinks in Valhalla and chose the dead in battle, but were not warriors in the same way as shield-maidens in the sagas.

Examples of shield-maidens mentioned by name in the Norse sagas include Brynhildr of the Vǫlsunga saga, Hervor in Hervarar saga ok Heiðreks, Brynhildr of the Bósa saga ok Herrauðs, and the Swedish princess Thornbjǫrg in Hrólfs saga Gautrekssonar. Princess Hed, Visna, Lagertha and Veborg are female warriors named in Gesta Danorum.

Two shield-maidens appear in Hervarar saga. The first of these Hervors was known to have taken up typically masculine roles early in her childhood and often raided travelers in the woods dressed as a man. Later in her life, she claimed the cursed sword Tyrfing from her father's burial site and became a seafaring raider. She eventually settled and married. Her granddaughter was also named Hervor and commanded forces against attacking Huns. Although the saga remarks on her bravery she is mortally wounded by enemy forces and dies on the battlefield.

Saxo Grammaticus reported that women fought on the side of the Danes at the Battle of Brávellir in the year 750:

Now out of the town of Sle, under the captains Hetha (Heid) and Wisna, with Hakon Cut-cheek came Tummi the Sailmaker. On these captains, who had the bodies of women, nature bestowed the souls of men. Webiorg was also inspired with the same spirit, and was attended by Bo (Bui) Bramason and Brat the Jute, thirsting for war.