Apple - Is it possible to crop multiple pages in Mavericks Preview.app?
Yes.
- Open a PDF.
- If not already enabled, View → Thumbnails.
- Select some pages (click first then select all; command+click or shift+click)
- Use the rectangle tool to select region on page. (On versions of OS X prior to 10.9, you should see a preview of the selection on other pages too).
- Select Tools → Crop (or Command+K). All your selected pages should be cropped.
- Save or Save As.
This is only possible when editing a pdf. It isn't possible to apply a single crop to many images that are in separate files. In order to do this, one way would be to
- Combine the images into a single pdf
- Open all of them in a single window.
- Use "Print" then "Save as pdf."
- Use the technique described in the other answer to crop all pages of the resultant pdf.
- Split the images back out into separate files using a variety of techniques, such as Automator's "Render PDF Pages as Images" function, or on the command line using ImageMagick as described here.
Note: if you're willing to use the command line, you might just want to use ImageMagick directly to crop all of the images.