Lion

Lions were a species of mammal native to Earth.

Lions lived in Greece in 16th century BC, though they later died out. When the Tenth Doctor and June visited the place where there would later be the Parthenon, they were attacked by lions. The Doctor defeated one and they both escaped. Later, when they were leaving, they encountered the lions again, which the Doctor subdued by tickling with his sonic screwdriver. (NSA: The Stone Rose)

Ian Chesterton saw a lion while imprisoned in the city of Rome. It was intended that he fight the beast but this event was changed in favour of a duel for Nero. (DW: The Romans)

Several Endovorms - who had the appearance of stone lions - were used by the Sevakrill to guard Nelson's Column while they installed a missile in it. (ST: The Lions of Trafalgar)

In an alternate timeline, lions survived despite the Silurian's reintroduction of extinct species. In Africa, Baryonyx would kill and feed on gazelle and leave the scraps for the lions. (NA: Blood Heat)

K9 once encountered lions on an unnamed planet in another dimension, partially inhabited by ex-Tellac miners. They lived alongside other Earth animals from widely varying periods of evolutionary history. On this planet, prides of lions lived around acacia trees, males in the branches, females in the shade underneath. (AK9: K9 and the Missing Planet)

The Third Doctor and the Brigadier once encountered a lion in a British zoo that was as docile as an ordinary house cat. This odd behavior convinced the Doctor and UNIT to investigate the strange goings-on in the area. (TVC: The Arkwood Experiments)

On a visit to the Ngorogoro Crater in 1926 the Seventh Doctor was reminded of a time when he, perhaps in another incarnation, saw the last lion on Earth shot in the same area. (DWM: Prelude Birthright)

Cultural references to lions

 * The Lion, the Witch and the Wardrobe was a book by C. S. Lewis. (DWM: The Professor, the Queen and the Bookshop)
 * In Pete's World, Mr Crane had "track 90" played once a large-scale cyber-conversion was underway in London. This song referred to sleeping lions. (DW: Rise of the Cybermen)
 * Nelson's Column, a monument to Horatio Nelson, had 4 lion statues around it. (DW: The Dalek Invasion of Earth)