Immutable configuration of virtual computer systems

Components associated with the management, instantiation, and control of instances, such as virtual machine instances, are configurable for immutability. In some embodiments, immutability is requested for one or more functionalities affecting or otherwise associated with an instance. Information regarding the request, as well as the requested immutability, may be propagated to one or more components, such as management components, for enforcement. Instances configured to have some or part of their functionality designated as immutable may be used to implement some or all of the management components themselves, and thus be used as a part (or entirety) of a management subsystem for other instantiations.