Ru-Shan Wu has made seminal contributions in many research areas in geophysics, such as seismic-wave propagation, scattering, imaging, and inversion. We highlight some of his research in holography imaging, diffraction tomography, seismic-wave scattering and its applications to studying Earth’s heterogeneity, oneway wave propagation and one-return wave modeling, beamlet and dreamlet applications, strong non-linear full-waveform inversion, and direct envelop inversion.