How do I play mkv files on my mac?

You use VLC player, its free:

http://www.videolan.org/vlc/download-macosx.html

I use either VLC or MPlayerX, both free.

VLC will play almost anything you through at it, so it's handy to have it around, but MPlayerX has a nicer interface, so it's usually my first choice.

You can download them here:

• VLC: http://get.videolan.org/vlc/2.2.1/macosx/vlc-2.2.1.dmg
• MPlayerX: http://mplayerx.org/download.html

PS: Be careful while installing MPlayerX. It started using an installer a few months ago and the installer might install adware if you don't disable it.

Some Progress on MPlayerX

Handbrake is my free drug of choice. Can convert MKV to just about anything including .mp4 that will play in QuickTime, or VLC.

VLC is indeed a good MKV Player for Mac, it can almost play all video, however, if you want to sync your videos to other Apple products such as iPhone, Apple TV, iPad mini, you need to convert them to some proper formats, what i use is the Video Converter, it can convert all videos to Mac and other Apple products comptible formats.

Hi I've found an easy solution, have only ran a couple of tests so far so can't fully vouch for it but I've been trying for some time and this is the best and quickest.
It's called Plex, kind of a multimedia cross platform steaming service. So far it works without glitches for AAC, AC3, DTS, DS 5.1 the setup is a bit weird but the main thing is it works all my BDrips in MKV play in HD. I will supply more feedback after a bit more testing.
Regards ZSquirrel

You can try ATK Player

https://itunes.apple.com/us/app/atk-player/id477735233?mt=12

It's the smoothest video player for Mac OS X. It also support 3D videos. So you can enjoy 3D videos at home.