The Landgraviate of Hesse (German: Landgrafschaft Hessen) was a principality of the Holy Roman Empire.

Upon the extinction of the ducal Conradines, these Rhenish Franconian counties were gradually acquired by Landgrave Louis I of Thuringia and his successors.

The remaining Thuringian landgraviate fell to the Wettin's Henry III, Margrave of Meissen.

Henry I of Hesse was raised to the status of prince by King Adolf of Germany in 1292.

The Landgraviate rose to primary importance under his son Philip I, also called Philip the Magnanimous, who embraced Protestantism following the 1526 Synod of Homberg and then took steps to create a protective alliance of Protestant princes and powers against the Catholic emperor Charles V. When Philip I died in 1567, Hesse was divided between his sons from his first marriage, which decisively enfeebled its importance.