Source: Bestiary, pg(s). 210
A Mummy is an undead creature created by a long and gruesome embalming process which involves removing all the major organs from a corpse and replacing them with herbs and flowers. The body is then wrapped in bandages, and animated with magic.
A typical mummy is of low intelligence, and is generally used as a tomb guardian.
However, it also possible to create free-willed mummies that retain some of the powers they possessed in life, such as spell-casting. These are often royalty that wish to extend their rule from beyond the grave and / or escape the fate that awaits them in the afterlife.
Infamous mummies in Golarion include :-