Parole is the video and media player for the XFCE4 desktop. It has a simple and unobtrusive interface, utilizes GStreamer for maximum audio/video format coverage, and requires few resources. It provides a couple of plugins however, such as notifications and systray integration or remote control support.
ExMplayer is a neat front-end for MPlayer with 3D/2D-video playback support. It also provides for media conversion, cutting and extracting; understands all common video, audion and container formats. ExMplayer also provides thumbnail previews for seeking per default, built-in subtitle search and downloading.
mrViewer is a compact video player, image/slideshow management tool, and flipbook viewer. It has a non-intuitive but feature-packed GUI and web interface; supports various video and audio formats via ffmpeg, colorization filters, vectorscope, histogram, HDRI, multichannel, OpenEXR support through anaglyphs, network syncing, grease pencils for the flipbook, and multi-part EXR images in addition to standard graphic files.