J\"urgen Herzog and Srikanth Iyengar Koszul modules Abstract. This paper introduces a new class of modules over noetherian local rings, called Koszul modules. It is proved that when a local ring $R$ is either a complete intersection or Golod, all high syzygies of finitely generated $R$-modules are Koszul. A stronger result is obtained when $R$ is Golod: the ($2$\,emb\,dim $R + 1$)st syzygy of every $R$-module is Koszul. In addition, results are established that demonstrate that Koszul modules possess good homological properties; for instance, their Poincar\'e series is a rational function.