Cofelia

Cofelia, undercover on Earth as "Miss Foster", was a Matron, an outer space "super nanny", of the Five-Straighten Classabindi Nursery Fleet-Intergalactic Class in the early 21st century. She had her own sonic device known as the Sonic pen.

Matron Cofelia was employed by the Adiposian First Family to breed a new generation after the Family's breeding planet was "lost". She traveled across the galaxy to find obesity on a great scale, which lead her to Earth. Under the guise of Adipose Industries, she produced a drug that claimed to attract human fat cells and flush them when in fact it attracted them and galvanized them into an Adipose body. This was illegal because seeding a level 5 planet is against Galactic Law and Earth is level 5. She activated her drug using the power of the molecules in the human bodies that were supposedly to make the people lose weight.

After the Adipose young were galvanized, they removed themselves from human flesh and waited to be collected by Cofelia. When the Doctor interfered with her plans, she was stopped from killing one million humans in the birth process to creat one million Adipose. Instead, they all survived the birth method and the March of the Adipose had only ten thousand young.

A Nursery Ship arrived and beamed the Adipose onboard but the First Family, who knew what they were doing was illegal, decided to rid themselves of their accomplice. After the Adipose were beamed up, the Doctor and Donna tried to convince Cofelia to get away when she was in the beam. But when she didn't believe them the beam switched off and she fell to her death. (DW: Partners in Crime)