myTube - Windows YouTube player that keeps your video playing no matter what.
Minitube - Minitube is a YouTube desktop application.
FreeTube - FreeTube is an open source desktop YouTube player built with privacy in mind.
YouView - Browse, watch, convert, and download YouTube videos on your Mac faster, because YouView uses the core technologies of Mac OS X to play instead of Flash allowing video to run smoother on systems with lower specs.
NewPipe - NewPipe is a lightweight YouTube front-end for Android.
Tubbler - YouTube Movie Player for Mac OS X.