Cash Cow

The Cash Cow was the name given to a large creature used for illegal meat production near Cardiff on Earth in 2008. It was believed to have been taken from the sea when it was small, but due to a mutation which caused it to constantly grow it soon reached a massive size and nearly filled up the warehouse it was kept in. This mutation allowed the producers to harvest meat from it while it was still alive, as it would just grow back.

While the people who kept it imprisoned belived it to be just some mindless deep-dwelling undiscoverd sea creature, the Torchwood team discovered to their horror that the animal was actually sentient. When the team first found it, Jack said "Imprisoned, chained and drugged, welcome to planet Earth" and the creature then opened its eyes and focused directly on Jack, making a sound different from the pained moans it usually made. All of the team where horrified when they discovered the extent of the mutilations (a huge hole carved out of the animal's side the size of a small cave) but none more so than Jack, who was shocked by the extent of the suffering that the helpless being had been put through.

It was killed by Owen Harper of Torchwood Three when the team raided the building to find the origin of the meat. The keepers of the Cash Cow believed it was a non-sentient Terran creature from the depths of the ocean; however, Jack Harkness believed that it was not from Mutter's Spiral at all. (TW: Meat)

Behind the Scenes
The cash cow bears a resemblance to the "Chicken Little" creature in the novel The Space Merchants by Frederik Pohl and Cyril M. Kornbluth. However, "Chicken Little" was not sentient.