SMPlayer is a complete media player for Windows and Linux. It uses the award-winning MPlayer as playback engine which is capable of playing most video and audio formats (avi, mkv, wmv, mp4, mpeg... see list). It uses its own codecs, so you don't need to install any codec packs. You can also play DVD discs and Internet streams, supports an impressive list of features and options.
The list of supported formats encompasses both major audio and video codecs and does a good job of trying to differentiate itself from the competition. One of the best features is that the player will remember your settings per video, so if you quit the app in the middle of playing, it'll restart it with the exact same settings as before.
Subtitles are fully customizable, including color, font, and size, and it can stream in content from the Internet. The app also works on both Windows and Linux, and it's supported in more than 20 languages. There's also a karaoke filter, so you can remove the audio track.