The conjecture that the Artin L-function of any n-dimensional complex representation of the Galois group of a finite extension of the rational numbers is an L-function obtained from the general linear group
Artin L-Function, Langlands Program
Knapp, A. W. "Group Representations and Harmonic Analysis, Part II." Not. Amer. Math. Soc. 43, 537-549, 1996.