iStock and Shutterstock provide images of sheep. Along with photographs of individual sheep and herds, vector images and cartoons are available. Both sites offer royalty-free images. Freerange Stock also offers some images of sheep for free download.
iStock features an Essentials range, which includes the lowest-priced images, and a high-quality Signature range. Images are available to buy in sizes ranging from small to 3XL.
Shutterstock's images are also available in various sizes, and can be purchased with either a standard or an enhanced licence. The enhanced licence allows use of the image on merchandise, among other commercial uses.
Freerange Stock has a number of photographs of sheep available for free download, but the site requires registration to download the materials.