Windows Messenger是微软公司开发的即时消息客户端软件，内置于Windows XP中。能够同时登录到SIP和.NET Messenger Service。从版本5开始，它能在Windows 2000、Windows XP和Windows Server 2003中运行，但不包括Windows Vista。

Windows Messenger与Windows Live Messenger（前称MSN Messenger）是不同的，纵使名称相似。后者可以从微软的网站下载。此外，Windows Messenger与信差服务并没有关系，后者是Windows NT的LAN Manager组件中的一部分。

Windows Messenger is a discontinued instant messaging client included in Windows XP. Designed for use by both corporate and home users, it was originally created as a streamlined and integrated version of MSN Messenger. It was later upgraded in 2004, when it was made available for Windows 2000 and Windows Server 2003. Since then, its development stopped. It was superseded by Windows Live Messenger and Microsoft Lync.