Myfanwy

Myfanwy was a pteranodon kept by Torchwood Three as a pet.

History
Myfanwy was a pteranodon (TV: Meat), which came through the Rift in 2007. (TV: Everything Changes)

It was found hunting in the countryside, killing sheep at night. (TV: Everything Changes) Ianto Jones trapped it in a warehouse and persuaded Jack Harkness to help him catch it. (TV: Fragments) Ianto named it "Myfanwy" after a Welsh goddess who sang beautifully (the pteranodon's screeches sounded horrible). (WEB: torchwood.org.uk)

It became Torchwood Three's mascot and pet and an essential part of their everyday life, even taking part in a basketball game (TV: Cyberwoman)

Jack Harkness used the pteranodon to attack Lisa Hallett, mortally injuring her. (TV: Cyberwoman) The pteranodon survived the encounter. (TV: Meat)

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 it was destroyed by a Jamolean lance, Myfanwy seemed to take pleasure in feeding on the burnt corpse. (PROSE: Pack Animals)

It is unknown wheather Myfanwy survived the destruction of the Hub during the 456 incident.

Personality
Myfanwy came and went from the main base as it pleased, entering through a large opening in the ceiling. Jack Harkness trained it well enough that it it returned to the base on 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) The pteranodon also had a fondness for dark chocolate, (TV: Fragments) cod, (WEB: torchwood.org.uk) and would feed on birds which perched around Torchwood Three (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.