Some images provided by Martin Vorel licensed under CC0 - Public Domain license & Royalty free. He has a whole webpage full of cool photos all under public domain licenses.
Also thanks to Pexels. They provide a huge selection of images under the "Pexels License" (completely free to use).
Same goes for Pixabay. Their license is also pretty much as free as it gets.
Image from Men In Black (1997) is copyrighted by Sony Pictures, but used under fair use (nonprofit, substantiality).