  The late evolutionary stages of stellar evolution are a key ingredient for
our understanding in many fields of astrophysics, including stellar evolution
and the enrichment of the interstellar medium (ISM) via stellar yields. Already
the first interferometric campaigns identified evolved stars as the primary
targets because of their extended and partially optically thin atmospheres, and
the brightness in the infrared. Interferometric studies spanning different
wavelength ranges, from visual to mid-infrared, have greatly increased our
knowledge of the complex atmospheres of these objects where different dynamic
processes are at play. In less than two decades this technique went from
measuring simple diameters to produce the first images of stellar surfaces. By
scanning the extended atmospheres we constrained theoretical models, learnt
about molecular stratification, dust formation, and stellar winds, and there is
still a lot to be done. In this contribution I will review the recent results
that optical/infrared interferometry has made on our current understanding of
cool evolved stars. The presentation will focus on asymptotic giant branch
stars, and red supergiants. I will discuss the challenges of image
reconstruction, and highlight how this field of research will benefit from the
synergy of the current interferometric instrument(s) with the second generation
VLTI facilities GRAVITY and MATISSE. Finally I will conclude with a short
introspection on applications of a visible interferometer and of the the Planet
Formation Imager (PFI) to the field of evolved stars.
