Pokey Mummies are deceased Pokeys that have risen from the dead. They are seen inside the Dry Dry Ruins and hold the same characteristics as regular Pokeys. The only difference is that they're greenish-blue and have become poisonous. They only appeared In the original Paper Mario.
Pokey Mummies are similar in appearance and function to the Poison Pokey from Paper Mario 2. They are, however, apparently distinct from each other, as Poison Pokeys developed their toxic abilities naturally.