In this article, I have collected 10 icon themes to install and use on Ubuntu 15.04 and 14.10 or older. I have selected the themes randomly, but if you think I have missed a nice icon theme you can mention it in the comment form below.
To enable these themes under Ubuntu with Ubinty desktop environment, you can use Unity Tweak Tool:
sudo apt-get install unity-tweak-tool
Here is the