In the last five years the field of catalytic oligomerization and polymerization of olefins using complexes of late transition metals has been the most intensively developing area of post-metallocene catalysis. This review is devoted to detailed analysis of the influence of metal nature on the catalytic properties of systems based on complexes of iron triad metals. Some novel and developing areas of application of such complexes in olefin oligomerization and polymerization (ethylene trimerization, production of olefins with an odd number of carbon atoms and polyethylene waxes, targeted synthesis of heavy fractions of ethylene oligomers) are surveyed. Different approaches to the heterogenization of catalysts on various solid supports are considered. The bibliography includes 225 references.