Classification turns chaotic knowledge into regularity by systematizing a domain and providing a common vocabulary. Currently there is a lack of systematic and comprehensive studies in organization and classification of Grid faults. We address this gap with a multi-perspective Grid fault taxonomy describing an incident using eight different characteristics. It is hard to define a taxonomy of broad validity and acceptance that satisfies the vast number of requirements of the many Grid user communities. Nevertheless we proof that our taxonomy can serve as a solid basis for defining project-specific custom classification schemes by giving a concrete example created for a state-of-the-art Grid middleware environment.