Download Rainbow Hierarchy 2 Free Unity. 

Have you ever thought about highlighting often used objects in your scene? This simple but colorful asset allows you to do that!

With Rainbow Hierarchy, you can set a custom icon and background for any object in the Hierarchy window.

Just hold the Alt key and click on any object in your scene. A configuration dialog will appear, and you’ll be able to assign custom icon and background to the corresponding object. Your own one or chose from dozens of presets!