A few days ago, the Skype application on my mac started crashing on launches. I googled around and found the following solutions and fixed the problem.
Possible Causes :
1. Some webcam application call ecamm installed on your mac.
2. The Office 2016 Mac Preview (in my case)
1. Uninstall those applications you recently installed.
2. Re-install your Skype with fresh download from Skype website.
3. I will post as I found it on http://community.skype.com/t5/Mac/Skype-quite-unexpectedly-OS-X-Yosemite-10-10-2/m-p/3874773#M74441
Open a Finder window. Select the Go menu. Press and hold the alt key. You'll see Library showing up in the list. Click on Library. Double click Application Support folder to reveal its content.
Drag and drop the Skype folder to the trash. Empty trash. Open Skype.
And this works for me.. i hope it will work for you too. Have a good day. ;)
This is my mac specification in case you need to refer to.