Penguin

Frobisher morphs back into a Penguin. (COMIC: Where Nobody Knows Your Name)

Penguins were birds that lived in cold or wet places. They mostly gathered in polar regions. Antarctica was often associated to penguins due to their presence on the continent. (PROSE: EarthWorld)

Penguins mated for life and often appeared on greetings cards. (TV: Something Borrowed)

History

In 1970s London, the Third Doctor and the Brigadier encountered penguins at a zoo. They had dived into their pool to escape a flock of parrots which were attacking them, but the penguins attacked them as well. (COMIC: The Arkwood Experiments)

In 7214, specimen of penguins were held in a nature preserve in Antarctopolis, having Antarctica been urbanised. (COMIC: Prisoners of Time)

References

One of the TV shows Cal watched in her dream world was about penguins. (TV: Silence in the Library)

The Tenth Doctor insisted that the North Pole did not have penguins, contrary to popular belief. (PROSE: The Frozen Wastes)

Frobisher

Frobisher took on the form of a penguin as his wife Francine had been fond of them. He occasionaly changed between variations of the species. (COMIC: Voyager)

Alternate timelines

In an alternate timeline, penguins lived on the River Nile in Egypt. (TV: The Big Bang)