David Nikolaevich Klyshko (Давид Николаевич Клышко), (1929—2000) was a Russian physicist in the field of quantum optics and quantum information science, a professor at Moscow State University. His Habilitation thesis on the topic of spontaneous parametric down-conversion, "Multi-quantum and multi-particle transitions in radio spectroscopy and quantum radiophysics," was published in 1972. Klyshko is noted for several important theoretical contributions including the development of spontaneous parametric down-conversion theory, entanglement-based quantum imaging, nonlinear transformations in quantum optics, and the advanced wave model for describing correlations in photon interference experiments.