There are thousands of image editors can be found on internet. Some of them have a lot and some are just carrying a few features. Some of image editors have specialized tools as well as are specialized for operating system. Here the list only contains the image editors which can work on Windows.
My favorite is GIMP and Paint.NET when using on Windows. Pinta is also great image editor. It is the best alternative for Paint.NET to be used on Linux. Paint.NET is not available for Linux. Well, GIMP is basically Linux soldier ported to Windows.
I could create the list of hundred image editors but that will be just waste of time. So a small list and I am sure you will find the one special image editor from the list.