Hypervisor，又称虚拟机监视器（英语：virtual machine monitor，缩写为 VMM），在电脑上的软件，韧体或是硬件，能用来创建与运行虚拟机。

拥有Hypervisor，能被用来运行一个或多个虚拟机，这样的电脑被定义为是一台主体机器（host machine）。在上面运行的虚拟机，则称为客体机器（guest machine）。hypervisor可以用一个客体操作系统（guest operating systems）的外貌出现，提供虚拟的作业平台，负责管理其他客体操作系统的运作。在它之上运作的多个操作系统，共同分享了虚拟化之后的硬件资源。

A hypervisor or virtual machine monitor (VMM) is a piece of computer software, firmware or hardware that creates and runs virtual machines.

A computer on which a hypervisor is running one or more virtual machines is defined as a host machine. Each virtual machine is called a guest machine. The hypervisor presents the guest operating systems with a virtual operating platform and manages the execution of the guest operating systems. Multiple instances of a variety of operating systems may share the virtualized hardware resources.