VLC is the VideoLAN project's media player. It plays MPEG, MPEG2, MPEG4, DivX, MOV, WMV, QuickTime, mp3, Ogg/Vorbis files, DVDs, VCDs, and multimedia streams from various network sources. VLC can also be used as a streaming server that duplicates the stream it reads and multicasts them through the network to other clients, or serves them through HTTP.
MPlayer can handle most mpeg, avi and asf files, supported by many native and win32 DLL codecs. You can watch VCD, DVD and even DivX movies. Also features a wide range of supported output drivers. It works with X11, Xv, DGA, OpenGL, SVGAlib, fbdev, but you can use SDL and some low-level card-specific drivers, too!
Totem is the official movie player of the GNOME desktop environment based on xine-lib or GStreamer. It features a playlist, a full-screen mode, seek and volume controls, as well as keyboard navigation. It is capable of playing most any video format including DVDs and VCDs.
A GTK+ based a media player that can play all the audio/video formats that libxine supports. Currently, this includes MPEG1, 2, some AVI and Quicktime files, some network streaming methods and disc based media such as VCD, SVCD, DVD.
Kaffeine is a media player for KDE. While it supports multiple player engines, its default engine is Xine, giving Kaffeine a wide variety of supported media types and letting Kaffeine access CDs, DVDs, and network streams easily.