Three types of specimen-size-independent Weibull master curves, characterizing strength and failure of macroscopically homogeneous, brittle materials have been derived. These Weibull master curves are significant if an uniaxial tensile stress is applied to the investigated specimens, as, for example, in the case of quasi-static uniaxial tensile tests or, under some restrictions, in the case of quasi-static three- or four-point bend tests. In addition, the existence of th ree types of apparent fracture toughness master curves, which can be applied to any material undergoing brittle cleavage fracture such as ceramics, intermetallics, or structural steels at low homologous temperatures, has been established. Furthermore, the same is also valid for the specimen-size-independent Weibull master curves. The apparent fracture toughness master curves can be obtained, by performing fracture toughness tests, or simply by applying a mathematical transformation to the corresponding Weibull master curves, which have been evaluated from quasi-static uniaxial tensile or bend tests.