Bus

Buses were large, four-wheeled vehicles, sometimes with two floors, used on Earth, capable of transporting many more passengers than a standard automobile. They often bore numbers associated with routes so that passengers could know which specific bus to ride in order to get to a particular place.

The Twelfth Doctor once compared adventures to buses, in that one had to share them with people one wouldn't normally associate with, they rarely went where they were expected to, and they frequently demanded change. (COMIC: Epilogopolis)

History
Upon returning to London in 1965, one of Ian and Barbara's first acts was to use the bus system to sightsee around central London. They discovered that bus fares had gone up during their time away. (TV: "The Planet of Decision")

The Fourth Doctor, Sharon Davies and Beep the Meep caught a double-decker bus, the number 5A, in Blackcastle to escape the Wrarth Warriors. Despite the Doctor telling the bus conductor, "You must let us on this bus! The whole future of the galaxy is at stake!", the reply was, "Sorry, mate! No animals allowed on my bus -- except on a lead!" — necessitating the Doctor's having to tie his scarf around Beep's neck as a temporary lead. As the three boarded the bus, one worried-looking man thought, "Oh no! Please don't let them sit next to me!" (COMIC: Doctor Who and the Star Beast)

Nostalgia Tours converted a space cruiser to have the chassis of a bus when it was due to travel to Earth, 1959. It was capable of flight, and was powered by a Hellstorm Fireball engine, located in the rear trunk. It was destroyed by the Bannermen. (TV: Delta and the Bannermen)

The Eighth Doctor commandeered a double-decker bus after its driver was killed. (COMIC: Doctor Who and the Nightmare Games)

Iris Wildthyme's TARDIS assumed the shape of the number 22 bus that often circled Putney Common. (PROSE: Old Flames)

In 1843, the Metropolitan Police Service wrote off the deaths of seven civilians and a policeman as the result of a bus crushing them. They had in fact been killed by stone lions. (AUDIO: The Lions of Trafalgar)

By 1943, buses were one of the many facilities that were racially segregated in Montgomery, Alabama. Black passengers had to enter through and sit at the back, while white passengers could sit at the front. Some passengers from other races were permitted to use the "white-only" seating, such as Yasmin Khan, who was of Pakistani heritage but often misidentified as Mexican. Rosa Parks famously refused to give up her seat on a segregated bus to a white passenger on the first of December, 1955, leading to driver James Blake calling the police, who arrested her. The Doctor, Ryan Sinclair, Yasmin Khan and Graham O'Brien witnessed the incident that lead to the Montgomery Bus Boycott, which began a year-long campaign that ended racial segregation on American buses on the 21st of December, 1956. (TV: Rosa)

Dodo Chaplet, believing they had landed in Kew Gardens, told Steven Taylor that if she got lost, she would catch a bus to return to the TARDIS. (TV: The Ark)

A tour bus took Maria Jackson and Kelsey Hooper to the Bubble Shock! factory. Later, Sarah Jane Smith broke into the factory with one of these buses, crashing through the door. (TV: Invasion of the Bane)

In the 21st century, the Tenth Doctor caught a double-decker bus in London whilst trying to save the Mayor of London from time assassins from the 27th century by creating a decoy "soup" made of the Mayor's DNA for the assassins. In this time, the Doctor asking a passenger for a mobile phone to speak to Martha Jones in the future and running around the bus frustrated a passenger, who thought the Doctor was just being a weirdo, and eventually decided start going to work by bicycle instead. (COMIC: Bus Stop!)

The 200 was another London double-decker bus. It fell through a wormhole to the planet San Helios. Its sturdy construction and metallic frame protected the occupants. The Tenth Doctor fitted it with anti-gravity clamps, making it capable of flight; it was then flown through the wormhole to Earth. Lady Christina de Souza later flew off in it to avoid being arrested. (TV: Planet of the Dead)

In London in 2014, Alice Obiefune saw the number 81 bus with an advertisement for Hovish on its side. (COMIC: After Life)

Amy Pond and Rory Williams once caught a ride in a school bus in Utah in order to meet up with the Eleventh Doctor. (TV: The Impossible Astronaut)

In an earlier regeneration, River Song stole cars and on at least one occasion, a bus. (TV: Let's Kill Hitler)

In 2015, the Eleventh Doctor rescued an old woman from being hit by the number 14 bus in London when she and the bus driver were both distracted by reading. (COMIC: Give Free or Die)

Some time in Jo Grant's future, English buses were no longer red. (PROSE: Losing Track of Time)

On Segonax, an old, colourfully-painted bus formerly belonging to the Psychic Circus was guarded by a robot bus conductor. (TV: The Greatest Show in the Galaxy)

Parallel universes
In the Unbound Universe, a monastery near Caroline Hill in Hong Kong had a bus that picked up tourists from the waterfront. On the day of the handover, the Doctor, the Master, the Brigadier and the UNIT troops used the bus to quickly descend to the waterfront, where the TARDIS was, as part of their plan to dispose of a psychic parasite. (AUDIO: Sympathy for the Devil)