Douglas Adams died of a heart attack before finishing his latest novel, The Salmon of Doubt, which was a sequel in his Dirk Gently's Holistic Detective Agency series. Best known for writing The Hitchhiker's Guide to the Galaxy, it's a shame that such a humorous and intelligent author was struck down before his time. There are references to penguins in two of his novels.

1.The Hitchhiker's Guide to the Galaxy:
"Ford," he said, "You're turning into a penguin. Stop it."
"That's not the point!" raged Ford. "The point is that now I am a perfectly safe penguin, and my colleague here is rapidly running out of limbs!"

2.The Long, Dark Tea-Time of the Soul:
"Or, at least, one-tenth of the cabin trunks were full of vivid and often painful and uncomfortable memories of her past life; the other nine-tenths were full of penguins, which surprised her. Insofar as she recognized at all that she was dreaming, she realized she must be exploring her own subconscious mind. She had heard it said that humans are supposed to use only about a tenth of their brains, and that no one was very clear what the other nine tenths were for, but she certainly never heard it suggested that they were used for storing penguins."


The Hitchhiker's Guide to the Galaxy
The Long Dark Tea-Time of the Soul