The House of Estridsen was a dynasty that provided the kings of Denmark from 1047 to 1412. The dynasty is named after its ancestor Estrid Svendsdatter. The dynasty is sometimes called the Ulfinger, after Estrid's husband, Ulf Jarl. The dynasty also provided three medieval rulers of Sweden and one of Norway. Their family coat of arms became the coat of arms of Denmark and thereby influenced the coat of arms of Tallinn and the coat of arms of Estonia.

The Royal Court of Denmark does not differentiate between different royal houses among the early Danish kings, but uses the term "the descent of Gorm the Old" about all the pre-Oldenburg monarchs.. The term is "Gorm den Gamles slægt" — literally "Gorm the Old's lineage/family." It's also referred to as Jellingdynastiet, Gormslægten, or occasionally Jelling-slægten (the Jelling dynasty).

The name of the Estridsen dynasty recalls their acquisition of the Danish crown through the marriage of Ulf the Earl to Estrid Svendsdatter of the House of Knýtlinga, daughter of Sweyn Forkbeard and sister of Cnut the Great. Later genealogies (introduced by the Danish historian Jakob Langebek in the 18th century) trace the family from Jomsviking leader Styrbjörn the Strong, a scion of the Swedish royal family, who in turn is given a descent from legendary King Sigurd Hring, regarded as mythical by most modern historians (no actual sources mention such an ancestry). Reliable ancestry traces back no earlier than Ulf's own father, the obscure Thorgil Sprakling and grandfather Björn (in sources called Ursius), the latter thus alternatively being identified as the above Styrbjörn by Langebek.

The dynasty reached its peak with the Kalmar Union, when its members reigned as kings of Denmark, Norway and Sweden in personal union. The dynasty came to end in 1412 with the death of its last member Queen Margaret I. All of the subsequent monarchs of Denmark are cognatic descendants of the House of Estridsen.