Vegetarianism

Vegetarianism was the practice of not consuming meat in one's diet.

The Doctor
When Jo Jones, reunited with the Third Doctor, she was surprised to discover he was not a vegetarian, having remembered him as one. Their discussion about the hypocrisy of a man who saved lives eating another creature's flesh convinced him to try the vegetable option for dinner. (AUDIO: The Sacrifice of Jo Grant)

The Sixth Doctor became a vegetarian (TV: The Two Doctors) but according to one account, soon gave it up. (COMIC: Salad Daze)

The Doctor was strictly vegetarian during his seventh incarnation, (PROSE: Human Nature), additionally avoiding consuming sentient plant-based lifeforms (AUDIO: The Trial of a Time Machine) The Eighth Doctor kept up the practice, (AUDIO: Relative Dimensions) but inconsistently. (AUDIO: Worldwide Web)

The Ninth Doctor ate meat, (TV: Boom Town) although the Twelfth repeatedly scolded people for their habit of eating meat. (TV: Deep Breath, Last Christmas, The Pilot, World Enough and Time)

The Dream Lord assumed the Eleventh Doctor was a vegetarian, taunting him by calling him "veggie". (TV: Amy's Choice)

The Doctor's companions
Zoe Heriot was a vegetarian. (AUDIO: The Integral)

Jo Grant approved of vegetarianism, and often thought of becoming one. (PROSE: Catastrophea)

The Fifth Doctor's companion Peri Brown was a vegetarian and therefore balked at the thought of eating roast boar at a banquet thrown in their honour by Pharaoh Erimem in Egypt in 1400 BC. The Doctor advised her to pretend to have eaten it by moving it around her plate. (AUDIO: The Eye of the Scorpion)

Melanie Bush was a vegetarian from the age of thirteen. (PROSE: Millennial Rites) She believed that it was wrong to eat meat. (PROSE: Business Unusual)

Ace once pretended to be a vegetarian to infiltrate a group of eco-terrorists. (AUDIO: Animal)

Sam Jones was a vegetarian. (PROSE: The Eight Doctors)

Others
Margery Phipps was a vegetarian. (AUDIO: Council of War)

Colin Colchester-Price sometimes liked to eat vegetarian. (AUDIO: A Kill to a View)

After Mrs Wormwood confirmed the Bane's predatory instinct, Clyde Langer, disgusted, remarked that he was now officially a vegetarian. After two Bane Kindred members attempted to attack him and Luke, he remarked that he became vegetarian, now he's "Bane munchies" (TV: Enemy of the Bane)

Krampus considered herself a vegetarian, as she consumed energy instead of flesh. (COMIC: Holiday Special)