Perchta or Berchta ('Bertha'; German: [ˈpɛʁçta, ˈbɛʁçta]), also commonly known as Percht (German: [ˈpɛʁçt]) and other variations, was thought to be a goddess in Alpine paganism in the Upper German and also Austrian and Slovenian regions of the Alps. Her name may mean 'the bright one' or 'the bearer' (Old High German: beraht, bereht, from Proto-Germanic *berhtaz) and is probably related to the name Berchtentag, meaning 'the feast of the Epiphany'. Eugen Mogk provides an alternative etymology, attributing the origin of the name Perchta to the Old High German verb pergan, meaning 'hidden' or 'covered'. The exact origin or time of origin is unknown.

Perchta is often identified as stemming from the same Germanic goddess as Holda and other female figures of Germanic folklore (see Frija-Frigg). According to Jacob Grimm and Lotte Motz, Perchta is Holda's southern cousin or equivalent, as they both share the role of "guardian of the beasts" and appear during the Twelve Days of Christmas, when they oversee spinning.

Grimm says Perchta or Berchta was known "precisely in those Upper German regions where Holda leaves off, in Swabia, in Alsace, in Switzerland, in Bavaria and Austria."

Perchta had many different names depending on the era and region: Grimm listed the names Perahta and Berchte as the main names (in his heading), followed by Berchta in Old High German, as well as Behrta and Frau Perchta. In Baden, Swabia, Switzerland and Slovenian regions, she was often called Frau Faste (the lady of the Ember days) or Pehta or 'Kvaternica', in Slovene. Elsewhere she was known as Posterli, Quatemberca and Fronfastenweiber.

The mother of the Franks emperor Charlemagne may have had a related albeit unwitted influence, as it did the Visigoth queen Brunhilda on her own, into its medieval folklore, Bertha or Berthrada was said to be of long and wide feet, in effect taller than her husband called precisely, Pippin the Short and may have been the reason why Charlemagne inherited from her his unusual height.

In southern Austria, in Carinthia among the Slovenes, a male form of Perchta was known as Quantembermann, in German, or Kvaternik, in Slovene (the man of the four Ember days). Grimm thought that her male counterpart or equivalent is Berchtold.

Regional variations of the name include Berigl, Berchtlmuada, Perhta-Baba, Zlobna Pehta, Bechtrababa, Sampa, Stampa, Lutzl, Zamperin, Pudelfrau, Zampermuatta and Rauweib.

In some descriptions, Perchta has two forms; she may appear either as beautiful and white as snow like her name, or as elderly and haggard.