The Hörsel (German pronunciationⓘ) is a 56 km (35 mi) long river in Thuringia, Germany, right tributary of the Werra.

The Hörsel has its source as Kleine Leina in the Thuringian Forest in the immediate vicinity of the Rennsteig south of the 749 metre high Spießberga at the southern community border of Finsterbergen to Georgenthal.

After 8.4 kilometers of flow distance in the district Schönau vor dem Walde the Leinakanal branches off to the right.

Then the Hörsel reaches Eisenach, where it takes in from the right the approximately equally strong Nesse and the much smaller Michelsbach, from the left the Löbersbach and the Roten Bach.

Further west, in the Eisenach district of Hörschel - - the place of origin of the Rennsteigs - is its estuary (waters) into the Werra.

A pipeline from the Leina - and the (upper) Apfelstädt from the system Gera/Unstrut/Saale/Elbe - to the subsystem of the Nesse is the Leinakanal, which was already built in the Middle Ages to supply the city Gotha with water from the Thuringian Forest.