mpv

This is what Movist and mPlayer X should have become on recent versions of the OS. Loved those two projects on Snow Leopard but there's no other minimalist player which doesn't stall and break MKVs including VLC. mpv plays everything and plays it well.

Well... it's pretty minimalist indeed! Just tried it, based on the good reviews below but I'm really surprised that prefs don't even exist! :-o You have to learn who knows what cryptic language to set up config files, frankly I've got other things to do in life. The good thing is that it answers pretty fast when you click on the timeline and it works "out of the box" if you're not too fussy about customization. I'll keep it around for those rare cases when my usual players have difficulties with some file, but as I play a lot of subtitled movies, I prefer the level of customization that Movist has.

This is what Movist and mPlayer X should have become on recent versions of the OS. Loved those two projects on Snow Leopard but there's no other minimalist player which doesn't stall and break MKVs including VLC. mpv plays everything and plays it well.

Crashes when trying to open Youtube video.

Wow, this is a sleek minimalist marvel!!! It easily played a 4K 30mbit file that VLC or old Mplayer based players couldn't. I still love VLC, and vlc and mpv make a great media playing duo. The OSD does all I need and command-line settings make this incredibly flexible. Remember this has a minimal GUI, use the keyboard bindings to control it (which you can easily cutomise).

mpv can play all the video formats. Simple design without bells and whistles. Just works fine. It has some improvements in comparison with previous versions of MPlayer. I like this project.

MPlayer has been my favorite media player since its beginning.

A great alternative to MPlayerX. This version is way out-of-date. The latest version is 0.18.0. OS X builds can be found at http://sva.wakku.to/~chris/mpv_builds/. This is much faster than MPlayerX which has malware in the installer.

Fast and plays everything.

install it with homebrew, there's no better choice.