Embodiments of the present disclosure provide a functional assembly, a display device and a terminal. The functional assembly includes a sensor unit, a first light-guiding component and a camera. The sensor unit includes an emitter and a receiver. The emitter is configured to emit probe light. The first light-guiding component is configured to introduce the probe light and transmit the probe light to the outside through the camera. The receiver is configured to receive detection light through the camera, the detection light being formed by reflection of the probe light against an obstacle. The functional assembly, the display device and the terminal in the present embodiment increase an area of a display region effectively, hence realizing an effect of large-screen display.