Dassel is a town in southern Lower Saxony, Germany, located in the district Northeim.

Dassel dates back to the year 860 when it was mentioned in a deed of the Imperial Abbey of Corvey.

In 1022, Henry II, Holy Roman Emperor, in another deed referred to Dassel church.

Shortly thereafter, in 1315, he provided his acquisition with town rights because the surrounding region belonged to the principality of Brunswick-Wolfenbüttel, thus to enemies of the bishop of Hildesheim.

As a result of the Thirty Years' War, Dassel was merged with the diocese of Hildesheim in 1643.

The Gymnasium (college preparatory school) in Dassel is named after Paul Gerhardt.

Dassel is easily accessible by bus from the neighbouring towns of Einbeck and Stadtoldendorf.