A
As spoken by the Fourth Doctor, A (Morse code: .- (TV: The Man Who Never Was)) was the first letter of the alphabet, preceding B. (TV: The Masque of Mandragora)
As of 25 December 2006, about one-third of Earth's human population had A-positive blood. (TV: The Christmas Invasion)
A levels were a type of exam. (TV: Terror of the Autons, Dragonfire)
In November 1963, science teacher Ian Chesterton set his Coal Hill School class a problem with the letters A, B and C representing the three dimensions. However, Susan Foreman pointed out that he had not acknowledged two additional dimensions: D, which Ian reasoned was time, and E, which Susan revealed was space. (TV: An Unearthly Child)
Contingency Plan A was the name the Company gave to the process of releasing dianene to kill the population of a city. (TV: The Sun Makers)
While under mental attack by the Mandragora Helix, the Fourth Doctor and Sarah Jane Smith spoke the alphabet backwards to concentrate. (TV: The Masque of Mandragora)
When trying to remember "Young Parsons'" name, Professor Chronotis went through the alphabet with the Doctor and Romana II. They started with A, B, and C and eventually got to P, Q, and R before he skipped to X and Y. (TV: Shada, AUDIO: Shada)
As recorded in the Dalek Survival Guide, the 2150s Dalek invasion of Earth involving the First Doctor was part of a version of history "A" relative to "B" and "C". (PROSE: Dalek Survival Guide)
Rose Tyler got one A, two Bs, four Cs, and a D in GCSE science. (PROSE: Meet Rose)
Whilst the pair were surrounded by GeoComTex security guards within Henry van Statten's vault, Rose Tyler quipped that the Ninth Doctor would be "Exhibit A" in a collection of aliens. (TV: Dalek)
"A" was among the letters written on a set of wooden blocks in Room 802 of Albion Hospital, within which the Empty Child was questioned by Dr Constantine. (TV: The Doctor Dances)
In 2028, under the influence of Nobody No-One, a cardiogram once sung the alphabet from A to P. (AUDIO: A Death in the Family)
The Tenth Doctor and the entity possessing Sky Silvestry spoke the first fifteen letters of the alphabet simultaneously. (TV: Midnight)
In 2010, Amy Pond wore a gold necklace in the shape of the letter "A". (TV: The Eleventh Hour et al.)
Upon seeing the image of Joseph Serf, actually a hologram, Clyde Langer announced that he was "preparing to say the A word", clarifying to Sky Smith that he meant aliens. (TV: The Man Who Never Was)
