Windows Live Messenger

Windows Live Messenger, previously known as MSN Messenger, was an instant messaging client introduced by Microsoft in 1999, before being shut down in 2014.

Backgrounds
Chat window backgrounds were added in MSN Messenger 6.1, and removed in Windows Live Messenger 2011. All five were licensed from Getty Images.

Dynamic backgrounds
Four dynamic backgrounds were added in MSN Messenger 7.5. As they are animated, all four of these are Flash-based, although feature an underlying .jpg background that is not embedded within the .swf.

Windows Live Messenger 2009
Starting from Windows Live Messenger 2009, backgrounds at the top of the chat window were introduced, known as scenes. [todo: table; list is temporary]
 * Bamboo
 * Butterfly Pattern
 * Carbon Fiber
 * Cherry Blossoms
 * Daisy Hill
 * Dawn
 * Dottie Green
 * Flourish
 * Field
 * Grafitti
 * Mesmerizing Brown
 * Mesmerizing White
 * Morty
 * Robot
 * Silhouette
 * Violet Springtime
 * zune_01
 * zune_02
 * zune_03
 * zune_04
 * zune_05
 * zune_06

Windows Live Messenger 2011 and 2012
2011 featured a mostly different set of scenes from 2009. This time, the scenes have a much narrower aspect ratio, while there is also a smaller version of each scene that appears at the top of the contact list. Many of these are also based on Windows 7 wallpapers. [todo: table; list is temporary]
 * Bamboo
 * Bird Man
 * Bounce
 * Carbon
 * Cherry Blossoms
 * Dahlias
 * Daisy Hill
 * Dark Hearts
 * Desert
 * Flourish
 * Grafitti
 * Hostas
 * Metalwork
 * Misty Hills
 * Moonlight
 * Prairie
 * Psychedelic
 * Punga
 * Robot
 * Sky Turtle
 * Spore
 * Sporty
 * Sweet Monsters
 * Tugboat
 * Violet Springtime
 * Watercolor
 * Wildflowers
 * Windows Live
 * Zune Hearts

MSN/Windows Live Messenger 6.1 to 8.5
Display pictures were introduced in version 6.1. Most of these are higher res versions of ones that appear in Windows XP, except for Soccer Ball which is unrelated to XP's ball user account picture.

Windows Live Messenger 2009
2009 added many new display pictures, including most of Windows Vista's user account pictures, several new buddy display pictures (five of which are animated), and a few other pictures of characters. The previous display pictures remain intact, but are not included in usertiles.mct.

Windows Live Messenger 2011 and 2012
At this point, most of the pre-2009 display pictures were removed, along with the buddy ones from 2009. However, the following remained intact: the ones taken from Vista, the non-buddy ones designed specifically for WLM 2009, and Beach Chairs and Rubber Ducky. A few new animated avatars were also added; this section will only list those.