The International Astronomical Union recently adopted in its XXVI General Assembly a definition of planets in the Solar System. Changing 76 years of tradition, our Solar System has 8 planets and an increasing number of a new category of bodies named “dwarf planets”. According to the resolution: “A "dwarf planet" is a celestial body that has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape and has not cleared the neighbourhood around its orbit”. In a footnote, the resolution says: “An IAU process will be established to assign borderline objects into either “dwarf planet” and other categories.” In order to contribute to the establishment of this classification procedure, we analyze the problem of the minimum mass required to become a “dwarf planet”, either from the theoretical and the observational perspective. We propose a classification criteria based on the available information on the shape and size of TNOs, principally the direct or indirect estimates of the diameter and the estimates of the shapes from the lightcurves. We compile the available observational data con TNOs, and we present a list of more than a dozen icy “dwarf planets”.