Gas spring and gas damper assemblies include a flexible spring member. First and second end members are secured to opposing ends of the flexible spring member to form a spring chamber. The second end member includes an end member wall that at least partially defines a damping chamber within the second end member. A damper piston assembly includes a damper piston and an elongated damper rod. The damper piston separates the piston chamber into first and second chamber portions. A pneumatically-actuated control device is disposed in fluid communication with one of the first and second chamber portions. The control device is selectively operable to alter the functionality of the gas spring and gas damper assembly between spring and damper functionality and actuator functionality. Suspension systems including one or more of such gas spring and gas damper assemblies as well as methods of operation are also included.