Lie groups, Lie algebras and their representations
Software
For finite and discrete groups
GAP and its SAGE interface
The Group Names database
The LMF database (LMFDB) and its documentation
The atlas of finite group representations
The catalogue of lattices.
For Lie algebras and Lie groups
The Lie library of SAGE
The atlas of lie groups and representations and its software
Package LieART for Mathematica and its documentation.
General group theory
Rotman, An introduction to the theory of groups
Robinson, A course in the theory of groups
Finite and discrete groups
Gallian, Contemporary abstract algebra
James, The representation theory of the symmetric groups
Burrow, Representation theory of finite groups
Weintraub, Representation theory of finite groups:algebra and arithmetic
Isaacs, Finite group theory
Ashbacher, Finite group theory
Gorenstein, Finite groups
Carter, Simple groups of Lie type
Morris, Introduction to arithmetic groups
Bourbaki, Lie Groups and Lie Algebras, Chap 6
Davis, The geometry and topology of Coxeter groups
Humphreys, Reflection groups and Coxeter groups
Ohshika, Discrete groups
Lie groups and Lie algebras
Kirillov, An introduction to Lie groups and Lie algebras
Godement, Introduction a la theorie des groupes de Lie
Hilgert and Neeb, Structure and geometry of Lie groups
Onishnik and Vinberg, Lie groups and Lie algebras vols I & II
Sepanski, Compact Lie groups
Onishnik and Vinberg, Lie groups and algebraic groups
Serre, Complex semisimple Lie algebras
Humphreys, Introduction to Lie algebras and representation theory
Knapp, Lie groups beyond an introduction
Weyl, The classical groups: their invariants and representations
Brocker and Dieck, Representations of compact Lie groups
Fulton and Harris, Representation theory: a first course
Procesi, Lie groups: an approach through invariants and representations
Bourbaki, Lie groups and Lie algebras, Chaps 1-3 and Chaps 4-6
A wider viewpoint on representation theory
Etingof et al, Introduction to representation theory
Infinite-dimensional Lie algebras and superalgebras
See here.