Abstract: The co-evolution of plants and their pathogens is an example of an “arms race” between the virulence factors of pathogens and the immune system of the host plant. In this case, pathogens use a variety of strategies, including those based on molecular mimicry. In the genomes of phytopathogenic organisms of different groups, genes have been identified whose products are similar to certain groups of plant proteins—enzymes for cell walls destabilization, precursors of peptide phytohormones, etc. In particular, the ability to produce effectors that are used to alter the growth of the host plant and suppress its defense reactions has become widespread among phytopathogens from different kingdoms of the living world—bacteria, fungi, and animals (namely, nematodes). In our review, we will consider the main examples of molecular mimicry found in plant pathogens.