Plugin allows you to manually crop all the image sizes registered in your WordPress theme (in particular featured image).
NextGEN Image Cropper extends the NextGen Gallery plugin to allow cropping of images.
NextGEN Z Cropper is a plugin that resizes and crops(!) your pictures while uploading them (not only thumbnails!). If the picture does not match your
Adds cropping to backgroud images in the Customizer, like header images have.
WP SmartCrop will crop your images on-the-fly to match your CSS, keeping the main focal point in view.