A deformable mirror can include a reservoir containing a ferrofluid. The deformable mirror can also include a reflective face sheet covering a front side of the reservoir such that a back side of the reflective face sheet is exposed to the ferrofluid. The reflective face sheet can have a reflective surface on a front side of the reflective face sheet opposite the back side. The reflective face sheet can have a non-uniform thickness between the front and back sides of the reflective face sheet to provide stiffness for the reflective face sheet. In addition, the deformable mirror can include one or more electromagnets operable to generate a magnetic field that acts on the ferrofluid to deform the reflective face sheet. A deformable mirror system can further include a control system operably coupled to the one or more electromagnets to control the magnetic field and thereby a deformation of the reflective face sheet.