Mummies are not intrinsically Egyptian: a mummy is essentially a body (or a collection of organs) that have been preserved. The reason we tend to hold 'mummy' synonymous with 'Egypt' would be the meticulous fervour with which the ancient Egyptians preserved their dead. And the image of a zombie in bandages has helped to create a specific image in the public consciousness.
Mummies also tend to come in two distinct flavours (please do not try and taste mummies): natural and unnatural. Unnatural mummies are the kind we are most familiar with. Wrapping a corpse in bandages, freezing it in a secret lab, or embalming it are all methods of creating an unnatural mummy.
The natural variety might be a smidge more interesting - usually preserved by their environment, these bodies were not preserved for the purpose of exhibiting them. As such, they can generally give us the most honest picture of contemporary human beings.
Please note: the following article contains images of preserved dead bodies and the subject matter can get a bit macabre. Also Walt Disney isn't here - he wasn't frozen - it's a myth.