1. Windows CE - commonly found in handheld devices and embedded systems.
2. VxWorks - often used in aerospace, automotive, and industrial systems.
3. QNX - frequently utilized in automotive infotainment systems and medical devices.
4. Embedded Linux - can be found in a wide range of embedded systems, including routers and smart TVs.
5. FreeRTOS - commonly used in IoT devices and small embedded systems.