You may be looking for the titular whale.

Moby-Dick was written by Herman Melville. The first line of the book was "Call me Ishmael". Isaac was given a copy of the book by Mila Rraxhimi. (PROSE: The Earwig Archipelago)

In 1884, Captain Kybo read Moby-Dick to help him learn English. (AUDIO: Judoon in Chains)

Moby-Dick was one of the three Books of Knowledge of Ravolox. (TV: The Mysterious Planet)

The Sixth Doctor had read the book, later declaring that Melville was one of his favourite authors, whilst Evelyn Smythe had given up on the book before the ship had weighed anchor, finding it to be pompous and overblown. (AUDIO: Bloodtide)

The Seventh Doctor told Ace that he had tried over a hundred times to read the book, never getting past the first ten pages. (PROSE: Sunday Afternoon, AD 848,988) The Twelfth Doctor thought being tied to a chair might help, to get through it. "Honestly, shut up and get the whale." (TV: Extremis)