Awesome
GentlyUI
A custom UI solution by Gentlymad Studios. It's mainly purpose is to enable developers to create UI without having to learn Unity UI. This is achieved by UI Definitions written in C#. Also GentlyUI takes care to effectively pool and reuse UI elements. Additionally GentlyUI provides a set of custom UI elements that are written with best UX on PC in mind but won't fit all usecases. Mobile and Console UI is currently unsupported.
~ Use at your own risk ~