Ball Aerospace is currently under contract to Marshall Space Flight Center (MSFC) in Huntsville, AL to design, build, and test a state-of-the-art lightweight beryllium mirror for cryogenic space applications, the Next Generation Space Telescope Sub-scale Beryllium Mirror Demonstrator (SBMD). The mirror is manufactured from spherical powder beryllium and optimized for cryogenic use. This 0.53-meter diameter lightweight mirror (< 12 kg/m2) has been tested at MSFC at ambient and cryogenic temperatures down to 23 K, cryofigured for optimal performance at 35 K, and subsequently retested at cryogenic temperatures. In addition, Ball has a separate contract with MSFC for an Advanced Mirror system Demonstrator (AMSD) to fabricate and test an ultra-lightweight mirror system which extends the semi-rigid SBMD mirror design to a 1.4-meter point-to-point beryllium hexagon mirror, flexures, rigid body and radius of curvature actuators, and reaction structure. This paper will describe the SBMD mirror performance and its cryogenic testing and present an overview of the AMSD semi-rigid beryllium mirror.