The House of Habsburg ( /ˈhæps.bɜrɡ/; German pronunciation: [ˈhaːps.bʊʁk]), also found as Hapsburg, and also known as House of Austria is one of the most important royal houses of Europe and is best known for being an origin of all of the formally elected Holy Roman Emperors between 1438 and 1740, as well as rulers of the Austrian Empire and Spanish Empire and several other countries.

The House takes its name from Habsburg Castle, a fortress built around 1020–1030 in present day Switzerland by Count Radbot of Klettgau, who chose to name his fortress Habsburg. His grandson, Otto II, was the first to take the fortress name as his own, adding "von Habsburg" to his title. The House of Habsburg gathered dynastic momentum through the 11th, 12th and 13th centuries. By 1276, Count Radbot's seventh generation descendant, Rudolph of Habsburg, had moved the family's power base from Habsburg Castle to the Archduchy of Austria. Rudolph had become King of Germany/Holy Roman Emperor in 1273, but the dynasty of the House of Habsburg was truly entrenched in 1276 when Rudolph became sovereign ruler of Austria, which the Habsburgs ruled for the next six centuries.