The Weil (German pronunciation: [vaɪl] ⓘ) is 46.6-kilometre-long (29.0 mi) river in Hesse, Germany.

It is a left tributary to the Lahn river and the town of Weilburg is located next to its mouth.

The river flows exclusively through the Taunus mountain range with its source being located between the Kleiner Feldberg and Großer Feldberg mountains.

It flows through Schmitten, Weilrod and Weilmünster.

This article related to a river in Hesse is a stub.