  We study the shadow produced by a class of rotating black holes surrounded by
plasma. The metric for these black holes arises by applying the Newman-Janis
algorithm to a family of spherically symmetric spacetimes, which includes
several well known geometries as special cases. We derive a general expression
for the shape of the shadow in the case that the plasma frequency leads to a
separable Hamilton-Jacobi equation for light. We present two examples in which
we obtain the shadow contours and the observables resulting from them. In one,
we analyze Kerr-Newman-like geometries, including braneworld and Horndeski
gravity black holes, while in the other, we consider scalar-tensor 4D
Einstein-Gauss-Bonnet gravity spacetimes. In both cases, we find that the
presence of plasma leads to a smaller and less deformed shadow.
