Abstract: Thermal management systems are disclosed. One thermal management system includes a first element, a second element adjacent the first element, and an optional third element adjacent the second element and opposed to the first element. The first element and the optional third element include a flexible graphite article, which may have the same or different physical properties. The second element includes an insulation material, such as an aerogel-based insulation material or a porous polymer matrix such as an expanded polytetrafluoroethylene (ePTFE) membrane. Also disclosed are electronic devices that include the thermal management systems to manage the heat generated therein to reduce or eliminate hot spots or for other purposes.