F is for... Foster, Miss

Miss Foster was the CEO of Adipose Industries, based in London, who had created a revolutionary new slimming pill. The product's motto was "The fat just walks away", and those taking it reported losing a kilo in weight each night. Both the Doctor and Donna Noble, unbeknownst to each other, decided to investigate the company, suspicious of its claims. They were right to do so, as Miss Foster was really an alien - Matron Cofelia of the Five-Straighten Classabindi Nursery Fleet (Intergalactic Class). She was a nanny, employed by the Adipose First Family to hatch a new brood of children, following the loss of their breeding planet Adipose 3. Adipose children were created from fat cells, and the pills were producing a child each night, which Miss Foster's people would collect. The plan was to produce millions of offspring, but the investigations of the Doctor, Donna, and a journalist named Penny caused Miss Foster to bring her plans forward. Instead of just some kilos of fat being transformed into Adipose, the users would have their entire body broken down. The Doctor challenged Miss Foster, reminding her that it was illegal to do what she was doing on a Level 5 planet like Earth. When the Adipose First Family sent a spaceship to collect the youngsters, the Doctor realised that they would know of this illegality, and so get rid of any witnesses. Miss Foster was transported up to the ship, but half way there the transmat beam was cut off and she fell to her death.
She owned a sonic device, in the shape of a pen, which the Doctor threw in a rubbish bin.
In an alternate timeline, where the UK had been devastated by the crash of the replica Titanic spaceship, Miss Foster successfully turned 60 million American citizens into Adipose.

Played by: Sarah Lancashire. Appearances: Partners In Crime (2008).