If you spend a sizeable amount of time using Terminal on your Mac, it pays to customise the theme to your liking. Terminal app comes with a number of build-in themes such as Grass, Homebrew, Red Sands, Silver Aerogel, Ocean etc A Github user lysyi3m has created a mac-os-x-terminal-themes repository that you can download and add additional themes.
Visit the Github site to view the available themes in the collection. Click on the “Download ZIP” button to download the theme files to your Downloads folder. There are more than 140 theme files. To add a theme to the Terminal, simply select the theme file and open the file under Finder. You might need to press the Control key while opening the theme file to override default OS X security settings.