We define the notion of a complete N= 2 supersymmetric theory in 4 dimensions as one which has a maximal allowed dimension for a UV complete moduli space for the coupling constants, masses and Coulomb branch parameters. We classify all such theories whose BPS spectrum can be obtained via a quiver diagram. This is done using the 4d/2d correspondence and by showing that such complete N=2 theories map to quivers of finite mutation type. The list of such theories is given by the Gaiotto theories consisting of two 5-branes wrapping Riemann surfaces with punctures, as well as 11 additional exceptional cases, which we identify. Copyright © by International Press of Boston, Inc.