Myfanwy

Myfanwy was a Pteranodon kept by Torchwood Three as a pet. She was named by Ianto Jones after a Welsh goddess who sang beautifully (as, ironically, the Pteranodon's screeches sounded horrible).

History
Myfanwy came through the Cardiff Space-Time Rift to Cardiff in 2007, where she was found hunting in the countryside and killing sheep at night. (TV: Everything Changes) Ianto Jones trapped Myfanwy in a warehouse, and managed to tranquilise it with Jack Harkness' help. (TV: Fragments)

Myfanwy was subsequently kept by Torchwood Three in the Hub as a mascot and pet, and became an essential part of their everyday lives; one time it even took part in a basketball game with the team. (TV: Cyberwoman)

When Lisa Hallett attacked the Torchwood team in the Hub, Jack sprayed Lisa with a barbeque sauce that caused Myfanwy to mistake Lisa for food and to attack and injure her. (TV: Cyberwoman) Myfanwy survived its encounter with Lisa. (TV: Meat)

When Toshiko Sato unintentionally stopped the Hub's movement through time to avoid it being sent to the Sanctified by a Rift storm, Myfanwy was trapped out of sync with time with the Hub and Tosh. Myfanwy saved Tosh from falling to her death when the Harrowkind attacked, and carried her to the top of the tower. Myfanwy was subsequently returned with Tosh and the Hub. (COMIC: Rift War!)

When an Apatosaurus-like alien was accidentally brought into the Torchwood hub, Myfanwy tried to fight it, allowing Toshiko Sato to get to the armoury. After the alien was destroyed by a Jamolean lance, Myfanwy seemed to take pleasure in feeding on the burnt corpse. (PROSE: Pack Animals)

It is unknown whether or not Myfanwy survived the destruction of the Hub during the 456 incident. (TV: Children of Earth)

Personality
Myfanwy came and went from the Hub as it pleased, entering through a large opening in the ceiling. Jack Harkness trained it well enough so that it returned to the Hub upon hearing a signal from his wristwatch, it never attacked a member of staff, never made a mess and only ate food treated with a certain "barbecue sauce" which Suzie Costello had developed. (WEB: torchwood.org.uk, TV: Cyberwoman, PROSE: Pack Animals) Myfanwy also had a fondness for dark chocolate, (TV: Fragments) cod, (WEB: torchwood.org.uk) and would feed on birds which perched around the Hub. (PROSE: Another Life)

Behind the scenes

 * Torchwood Declassified mentions that the Pteranodon was nicknamed "Myfanwy" by the cast. This is later shown to be the case in-universe, when the Torchwood site featured an IM conversation between Ianto and Owen about Myfanwy's feeding habits. (WEB: torchwood.org.uk)
 * Jack refers to the beast as a dinosaur but it is not. Pteranodons were pterosaurs, flying reptiles, while dinosaurs only lived on the land.