Script Template Editor
With Script Template Editor you can easily make changes to the default templates, Unity uses when generating new files like C# and Shader scripts.
This extension is very useful for things like adding new default using statement, or for removing/replacing the default methods in your C# scripts.
Script Template Editor is always up-to-date. When Unity adds a new template type, it will automatically be found and added to the list of templates you can edit.
If you make a mistake or decide that you want the default templates back, you can always discard any changes you have made with the click of a single button.