The companions of Saint Nicholas are a group of closely related figures who accompany Saint Nicholas throughout the territories formerly in the Holy Roman Empire or the countries that it influenced culturally. These characters act as a foil to the benevolent Christmas gift-bringer, threatening to thrash or abduct disobedient children. Jacob Grimm (Deutsche Mythologie) associated this character with the pre-Christian house spirit (kobold, elf) which could be benevolent or malicious, but whose mischievous side was emphasized after Christianization. The association of the Christmas gift-bringer with elves has parallels in English and Scandinavian folklore, and is ultimately and remotely connected to the Christmas elf in modern American folklore.

Names for the "dark" or threatening companion figure include: Knecht Ruprecht in Germany, Krampus in Austria, Bavaria, Parkelj in Slovenia, Friuli, Croatia, Hungary (spelled Krampusz); Klaubauf in Bavaria, Austria; Bartel in Styria; Pelzebock; Befana; Pelznickel; Belzeniggl; Belsnickel in the Palatinate (and also Pennsylvania, due to Pennsylvania Dutch influence); Schmutzli in Switzerland; Rumpelklas; Bellzebub; Hans Muff; Drapp; and Buzebergt in Augsburg.

The corresponding figure in the Netherlands and Flanders is called Zwarte Piet or Black Pete, and in Swiss folklore Schmutzli, (schmutz meaning dirt). In the Czech Republic, Saint Nicholas or svatý Mikuláš is accompanied by the čert (Devil) and anděl (Angel). In France, Saint Nicholas' companion is called Rubbels in German-speaking Lorraine and Hanstrapp in Alsace, East of France and the Père Fouettard (Wallonia, Northern and Eastern France).