Leather

Leather was a material made by tanning animal skins. (TV: The Coach with the Dragon Tattoo)

After the death of Lucie Miller, the Eighth Doctor added more leather to his ensemble, specifically a navy blue leather peacoat. (AUDIO: Fugitives) The War Doctor wore double-breasted trenchcoats, making it suitable for battle. (TV: The Name of the Doctor, The Night of the Doctor, The Day of the Doctor) The Ninth Doctor wore a similar style as part of his main wardrobe, a black double-breasted peacoat. (TV: Rose et al.)

Some of the Doctor's companions wore leather jackets. They included Sarah Jane Smith (TV: The Monster of Peladon), Rose Tyler (TV: The Stolen Earth|Journey's End), Martha Jones (TV: The Shakespeare Code) Ace (TV: Dragonfire), Amy Pond, (TV: Victory of the Daleks), Clara Oswald, (TV: The Magician's Apprentice|The Witch's Familiar), and Yasmin Khan (TV: It Takes You Away)

Candy DuFries always carried a battered leather satchel full of watercolours. (PROSE: Eternity Weeps)

The symbiotic Fliis planned to take over humans on Earth in the 20th century. They disguised themselves as leather jackets to trick people into wearing and bonding with them. (COMIC: Fashion Victims)

In October 2016, Ram Singh suggested that a male skin-peeling dragon make Coach Dawson's skin into leather, "make a chair or something", in order to preserve his mate. (TV: The Coach with the Dragon Tattoo)

In the 24th century, hidehogs were genetically engineered animals used to produce leather. (PROSE: To the Slaughter)

The skins of ghouties could be made into leather. They looked like a cross between a donkey and a three-toed sloth and were found on Thanaxos. (PROSE: The Mary-Sue Extrusion)

The Slabs were made of leather. (TV: Smith and Jones)