The Lower Saxon Circle (German: Niedersächsischer Reichskreis) was an Imperial Circle of the Holy Roman Empire. It covered much of the territory of the medieval Duchy of Saxony (except for Westphalia), and was originally called the Saxon Circle (German: Sächsischer Kreis or Sächsischer Reichskreis) before later being better differentiated from the Upper Saxon Circle by the more specific name.
An unusual aspect of this circle was that, at various times, the kings of Denmark (in Holstein), Great Britain (in Hanover) and Sweden (in Bremen) were all Princes of a number of Imperial States.
The first plans for a Lower Saxon Circle originate from Albert II of Germany in 1438. An Imperial Saxon Circle was formally created in 1500, but in 1512 it was divided into an Upper Saxon and Lower Saxon Circle. The division was only codified in 1522, and it took a while before the separation was completely implemented by the Imperial Chamber Court. Furthermore, the first mention of an Upper Saxon Circle, a Lower Saxon Circle or the Netherlands occurred much later on. The term Lower Saxony (Niedersachsen) was first used only in 1548.
The Lower Saxon Circle included the easternmost part of current Lower Saxony, the northernmost part of Saxony-Anhalt (excluding the Altmark),Mecklenburg, Holstein (excluding Dithmarschen), Hamburg, Bremen, in addition to small areas in Brandenburg and Thuringia. For the most part it was a continuous territory with the exception of small enclaves like Halle and Jüterbog. Nordhausen and Mühlhausen were also areas outside the continuous portion of the imperial circle. Within the circle was the Archbishopric of Verden, which was in personal union with the Archbishopric of Bremen since 1502. The Counties of Schaumburg and Spiegelberg were also part of the personal union, but they were not a part of the Lower Saxon Circle.