Do other types of system software like servers, utilities, and device?
I think the answer is dependent on which operating system is being used and also on how you want to determine what the OS is. If you consider the OS to be nothing but the kernel then non of the mentioned software types is part of the OS. If you consider the OS to be part of the non user accessible system then device drivers could be considered part of the OS. Please note most OS allow programmers to add new device drivers. Usually this requires some special SDK that is not generally available to application writers. So at a minimum, device drivers are a special type of application or an extension of the OS. Servers and utilities are best thought of as applications and not part of the OS. If you have a utility that extends the shell or the UI of the OS, some might consider that part of the OS.