With the sole exception of System.Object, which does not inherit from any other object type, all object types shall either explicitly or implicitly declare support for (i.e., inherit from) exactly one other object type. The graph of the inherits-relation shall form a singly rooted tree with System.Object at the base; i.e., all object types eventually inherit from the type System.Object. The introduction of generic types makes it more difficult to give a precise definition; see Partition II Metadata - Security.
An object type declares that it shall not be used as a base type (be inherited from) by declaring that it is a sealed type.
System.Objectis CLS-compliant. Any other CLS-compliant class shall inherit from a CLS-compliant class.
Arrays are object types and, as such, inherit from other object types. Since array object types are manufactured by the VES, the inheritance of arrays is fixed. See §I.8.9.1.