There is also a variation called the Weil form of the L-group, where the Galois group is replaced by a Weil group. Here, the letter L in the name also indicates the connection with the theory of L-functions, particularly the automorphic L-functions. The Langlands dual was introduced by in a letter to A. Weil.

The L-group is used heavily in the Langlands conjectures of Robert Langlands.