RenaMe

RenaMe (say “ree-nay-mee”) is a compact editor utility to quickly rename things in bulk inside your Unity development environment.
You can rename anything from GameObjects to Assets to Folders (or even more if needed). All without losing any prefab connections, asset links, etc...
Want to remove those ugly underscores from certain file names? Select the affected files, add a Remove action to the list of renaming actions, type in "_" and hit Rename. You're done.
Want to replace every occurrence of the word "WIP" with "Final"? Same procedure. Different action. You can pile up multiple actions; they will be executed sequentially from top to bottom.
There are many default renaming actions that come with RenaMe, but thanks to the 100% fully accessible and clean source code you can easily create your own renaming actions: it's just the matter of implementing an interface.
Creating a new renamable type is also a breeze: you define what can be renamed and what can't! The code is well-commented and easy to understand (while still maintaining a good and professional architecture). More detailed information about the code structure can be found inside the Documentation.pdf