Medical Images

Depositphotos contains over 50 million affordable general images.

Dreamstime has over 50 million stock images and some free content.

Getty houses a large collection of imagery for every budget.

POND5 contains general high-definition stock imagery and video.

Creative Commons is a platform to search other third party sites for CC licensed material; however, don't assume that all results are under a CC license. Check the source of the image before reusing.

Flickr Commons shares public photography archives with the world.

SSO is a free, open-access library of images.

Unsplash contains high-resolution photos all licensed under a Creative Commons Zero license. Use a photo or submit one of your own.

Wikimedia Commons is a database of freely usable files. Use a file or submit a file of your own.

Use TinEye to search for images using images.