Three main categories of animal mummies existed in ancient Egypt:
- Pets buried with their owner in a tomb. These were usually mummified with the same care as humans were.
- Animal mummies sold to the public as offerings to the gods. In the later periods, many sacred animals were specifically bred so they could be used as offerings. Many of these were not well mummified, some contained only rubble or only parts of an animal. X-rays show that numerous animals had broken necks or battered skulls, indicating they were deliberately killed for this purpose. This could mean that some buyers were being deliberately deceived or that only the external appearance of the mummies was required to fulfil the religious function of these offerings.
- Temple animals preserved for religious reasons (such as the Apis bull). There were usually only one of these animals alive at a time. This animal was believed to be the physical manifestation of a god. Priests would travel throughout the country in search of the right creature with the proper markings on the body. Once they had identified one, it was fed and nursed in the temple until its death, when it received an individual burial after extensive mummification.