Messenger Plus! Live (known more as its former name Messenger Plus!, commonly abbreviated MsgPlus, MP!L, or incorrectly as MSN Plus) is a freeware add-on for Windows Live Messenger created by Patchou. The software provides additional functionality to Microsoft's Windows Live Messenger by adding its own controls to the main interface. These controls affect Messenger's behaviour and appearance, often through additional dialog boxes.

The add-on was first released in May 2001 under the name "The Messenger Plus! Extension" for MSN Messenger and Windows Messenger. It later changed its name to "Messenger Plus!" and then, for the release of the new Windows Live Messenger client, "Messenger Plus! Live" was chosen. It has become one of the most widely used add-ons for Microsoft's IM clients, citing over 300 million downloads as of December 2007 .

Messenger Plus! Live 4.50, released on the 9th of December 2007, is the latest branch and contains many new features (such as skinning), visual improvements and bug fixes.