The physics of wave propagation in disordered, structured or nonlinear media is at the heart of various research fields covering disordered quantum gases, electromagnetic or ultrasounic waves in scattering or biological media, wave-front shaping or nonlinear imaging. This 5th annual meeting of the GdR Complexe aims at gathering physicists to discuss these topics and their connections, as well as to identify emerging questions around the propagation of waves in complex systems in a broad sense.