Various thermal energy conversion systems have been reviewed in order to select an efficient power cycle that is compatible with fusion reactor requirements. The most suitable power cycles were selected for a toroidal confinement system with deuterium-tritium and deuterium-deuterium fuel cycles and for a tandem mirror reactor (TMR) with a D-3He fuel cycle. The steam cycle was found to be most suitable for the reversed-field pinch and tokamak reactors, whereas a combination of a direct energy conversion system and a steam cycle was found to be most suitable for a D-3He TMR. It is anticipated that the energy conversion systems of all fusion reactors fall under these two categories.