The designation E8 comes from the Cartan–Killing classification of the complex simple Lie algebras, which fall into four infinite series labeled A"n", B"n", C"n", D"n", and five exceptional cases labeled E6, E7, E8, F4, and G2.
The designation E8 comes from Wilhelm Killing and Élie Cartan's classification of the complex simple Lie algebras, which fall into four infinite families labeled A"n", B"n", C"n", D"n", and five exceptional cases labeled E6, E7, E8, F4, and G2.