The Doctor's fur coat

 was a fur coat used and worn by the Second Doctor in cold weather.

The coat was made of polyester rather than animal skin and was bought by either the First or Second Doctor on the planet Thraxis. (AUDIO: No Place Like Home)

The Doctor wore it during his second incarnation when visiting the Himalayas. He wore the coat to protect himself from the cold, but the coat led him to being mistaken for the Robot Yeti who had been killing villagers. The Doctor was able to prove his innocence and stop the Yeti. (TV: The Abominable Snowmen)

The Doctor wore the coat again when encountering the Ice Warriors. (TV: The Ice Warriors)

He wore the coat while on an adventure, running past one of the many versions of Clara Oswald after she entered the Doctor's time stream. (TV: The Name of the Doctor)

He wore the coat when he visited his old friend the Brigadier in the 1980s. He and the Brigadier were captured and taken to the Death Zone on Gallifrey. He was able to take them home. (TV: The Five Doctors)

At one point, the Fifth Doctor stopped and studied the coat in the TARDIS wardrobe. (AUDIO: No Place Like Home)

The Sixth Doctor once donned his predecessor's fur coat, recalling how useful it had been against the Yeti. (AUDIO: Beyond the Ultimate Adventure)

The Seventh Doctor once tried the coat on while trying to find a new costume. He hid his new costume under it. (TV: Time and the Rani) He later donned it again when he encountered the Ice Warriors with Frobisher (COMIC: A Cold Day in Hell!) and again when exploring an ice world. (PROSE: Cold Fusion)

Behind the scenes

 * The appearance of the Second Doctor in his fur coat in The Name of the Doctor was archive footage taken from The Five Doctors.