Research on “post‐metallocene” polymerization catalysis ranges methodologically from fundamental mechanistic studies of polymerization reactions over catalyst design to material properties of the polyolefins prepared. A common goal of these studies is the creation of practically useful new polyolefin materials or polymerization processes. This Review gives a comprehensive overview of post‐metallocene polymerization catalysts that have been put into practice. The decisive properties for this success of a given catalyst structure are delineated. “Post‐metallocene” polymerization catalysis research ranges from fundamental mechanistic studies by catalyst design to material properties of polyolefins. A common goal of these studies is the creation of practically useful new materials or processes. A comprehensive overview of post‐metallocene polymerization catalysts that have been put into practice is provided. The decisive properties for this success of a given catalyst structure are delineated.