Abstract: A foldable reflector umbrella has a flexible, cloth-like reflective element with an outer supporting and tensioning structure composed of a plurality of tensioning spokes which are preferably distributed evenly over the expanse and divide the reflective element into a number of umbrella segments essentially corresponding to the number of tensioning spokes. With the reflector umbrella in the opened state, the reflective element consisting of the number of umbrella segments forms a substantially rotationally symmetrical body with a light exit opening. The reflector umbrella has a cloth-like reflective element in the opened state that is at least partially gathered so as to form an uneven reflection surface. A reflector assembly including a reflector umbrella is also provided.