Janet (Everything Changes)

Janet was the name to which the team of Torchwood Three referred to a specific Weevil, who was caught by Torchwood 3. Janet was kept in the Torchwood cells and was kept as a secondary pet (next to Myfanwy) to Torchwood.

History
When Jack Harkness was telling Gwen Cooper about the origin of the Weevils, he showed her Janet. (TW: Everything Changes)

When Gwen was interrogating the Sex Gas that was controlling Carys Fletcher, she turned to another cell and was frightened when Janet jumped up. (TW: Day One)

When a Weevil was killed by a person infected an alien tapeworm, Janet started whistling to mourn. Later, when Marianne Till, another victim of a tapeworm, was brought to the Torchwood cells, Janet was frightened of her and kept away from her cell. (TWN: Slow Decay)

When Torchwood was trying to find the Weevil Fight Club, they let Janet loose and followed her telepathic senses to where she would try to free her kind. She was abducted by the Fight Club, and used as a wrestler, but after they were shut down, she ended up with Torchwood again. (TW: Combat)

When the cells went offline, Janet escaped, but was trapped in the hold along with Rhys Williams, who was being kept safe by Gwen. Janet did not kill Rhys, but Bilis Manger did, frighting Janet. (TW: End of Days)

When trying to prove to an undercover Sleeper Agent that there was such things as aliens, Jack threatened to feed her to Janet. (TW: Sleeper)

When interrogating Billy Davies, Ianto Jones brought in Janet, whose chain brought her mere inches away from him. Ianto got rid of her by using anti-Weevil spray. (TW: Reset)

When Weevils began to worship Owen Harper because he was a key for Durac to enter this world, he tested this by sticking his finger into Janet's pen, she didn't bite it off. (TW: Dead Man Walking) Even after Durac died, Janet was still distressed around Owen. When thinking about his death, Owen stood by Janet's pen, watching her cowl away. (TW: A Day in the Death)

Janet was later released from her cell by Gray. She then attacked Gwen Cooper and John Hart, but was shot and wounded by Ianto Jones. She was then returned to her cell. (TW: Exit Wounds)

Janet was probably destroyed along with The Hub. (TW: Children of Earth: Day One)

Behind the Scenes

 * In Torchwood, Janet is credited as Weevil, even after her name's revelation.
 * Her name as Janet was revealed in Combat, but the rest of the team were oblivious to Jack's naming of her. Jack uses the name "Janet" to introduce the hidden Sleeper to her.
 * Beyond the name, there is little to indicate whether Janet was, in fact, a female Weevil, and the character was played by a male actor.