KMPlayer
KMPlayer is a a fully-featured media player. It can handle a variety of media formats including VCD, DVD, AVI, MKV, Ogg, OGM, 3GP, MPEG, Windows Media, RealMedia and QuickTime formats, has support for captions, and can also play damanged, incomplete, locked or compressed media files.
An advanced feature is the ability to capture audio, video and image screenshots from your media.