The International Committee of Foundry Technical Associations has identified seven basic categories of casting defects: metallic projections, cavities, discontinuities, defective surfaces, incomplete casting, incorrect dimension, and inclusions or structural anomalies. This article presents some of the common defects in each of the seven categories in a table. It discusses common defects determined during the examination of samples of ductile cast iron in Elkem's research facility in Norway. The article reviews common defects, such as shrinkage cavities, blowholes, hydrogen pinholes, nitrogen defects, and abnormal graphite morphology, found in gray iron. It concludes with a discussion on surface defects in compacted graphite iron.