Bear

Bears were mammals native to the planet Earth.

Terrestrial bears
The Doctor, their companions and acquaintances encountered bears on several occasions.

Prior to his fifth incarnation, the Doctor had a bear but he had to release it when it started eating his bedroom furniture. (AUDIO: Cuddlesome)

In 100,000 BC, Za vowed to kill bears and bring their skins to the Tribe of Gum, although Horg doubted that he would do so. (TV: An Unearthly Child)

About 120 AD, the Tenth Doctor found himself opposing lions, tigers and bears in the Flavian Amphitheatre. When the bear approached, the Doctor quickly climbed a tree, losing his sonic screwdriver in his haste. He dropped on the back of the bear, scooped up his screwdriver and gave the beast a burst at the right frequency. The bear meandered away. (PROSE: The Stone Rose)

The First Doctor's sodden coat made him feel like he was wearing a bear. (PROSE: A Big Hand for the Doctor)

In November 1988, Richard Maynarde thought he heard a bear. Lady Peinforte reassured him that it would not follow them because such things happened only in the theatre. (TV: Silver Nemesis)

Bears were listed in the Avalonian Bestiary of all animal life on the Earth colony Avalon. (PROSE: The Sorcerer's Apprentice)

In the year 5000, Jamie and Elric Penley were attacked by a bear. Penley tranquillised it, but was clawed while doing so. (TV: The Ice Warriors)

Lynda Moss told the Ninth Doctor about a popular television series called Bear With Me, a show about three people living with a bear. (TV: Bad Wolf)

These incidents combined, ranging from the 2nd century AD to the year 200,100 indicated that bears, in general, were a hardy species, not threatened by extinction across many millennia.

Species
On Earth several specific Species of bear were known, including the cave bear, panda and the polar bear.

Animals similar to bears
The Yeti species Yeti Traversii were more bear-like compared to fellow Yeti Mih-teh and Dzu-teh, who were closely related to apes. (PROSE: Downtime)

The skeleton of a Heavenite was identified by Benny as "probably something like a bear with an opposable thumb". (PROSE: Love and War, AUDIO: Love and War)

Products related to bears
During a leadership struggle, Za promised to kill many bears the next day to provide warm skins for his tribe after Kal brought the First Doctor, whom Kal saw producing fire. (TV: "An Unearthly Child")

Bears were often taxidermal subjects. Hex once came across a seven-foot stuffed bear. The Seventh Doctor said it was used by a university for anatomical demonstration. (AUDIO: Night Thoughts)

Toy stuffed bears — in the form of anatomically incorrect teddy bears — were also popular on Earth, from around the late 19th century. (TV: The Snowmen and others)

Winnie the Pooh, a storybook character, was an anthropomorphic bear. (PROSE: Fallen Angel, Time and Relative, et al.)

Extraterrestrial bears
Horned bears were among the native lifeforms of Tiermann's World. (PROSE: Sick Building)

The Doctor once said he had a bear when he was young, but he had to release it when it started eating the furniture. (AUDIO: Cuddlesome)

On Hyspero, Angela ruled over the bears of Kestheven, who shaved their golden fur and went about hairless. (PROSE: The Scarlet Empress)

Solar bears lived in the ice clouds of New Earth, deriving their energy from the sun. (AUDIO: The Skies of New Earth)

Other references
Despite being based off a panda bear, Panda often took offence to being called a "bear". (AUDIO: Wildthyme at Large)