The Silence


 * For the species identified as the leaders of "The Silence", see Silent.

The Silence was a religious order, considering themselves the “Sentinels of History”, who tried to kill the Doctor because of a specific prophecy, which states: “On the fields of Trenzalore, at the fall of the eleventh, when no living creature can speak falsely or fail to answer, a Question will be asked. A question that must never, ever be answered.”

The Question is revealed to be the “The First Question, the oldest question in the Universe, that must never be answered, hidden in plain sight.” Dorian Maldovar tells the Doctor what the question is--“Doctor Who?”

Organization
The Silence was led by a race of memory-proof aliens (known as the Silents) who used post-hypnotic suggestion to manipulate other species into doing their bidding. These aliens also employed human or humanoid agents to carry out specific tasks. These agents were often fitted with an Eye Drive, which allowed them to remember the Silence.

History
The Silence were possibly the mysterious entity that forced the Doctor's TARDIS to explode on 26th June 2010, creating cracks in time that would erase things throughout the universe, and eventually the universe itself. Although the entity that caused the Doctor's TARDIS to explode was never visible or named, a voice was heard speaking before the TARDIS began exploding, stating "Silence will fall!" (DW: The Pandorica Opens / The Big Bang)

The Silence also indirectly played a hand in the destruction of the Saturnyns' homeworld. In 1580 Venice, Rosanna Calvierri said that through some of the cracks, the Saturnynians saw only "silence and the end of all things." This caused them to flee their homeworld to 1580 Earth through a different crack that acted like a wormhole. (DW: The Vampires of Venice)

The alien leaders of the Silence were encountered by the Doctor in 1969 America. The Silents had been operating on Earth since the Stone Age, working to secretly manipulate Humanity towards their own goals. It is implied that they were responsible for the Moon Landing, because they needed a special space suit for Melody Pond. The Silence's occupation of Earth, however, was broken when the Doctor issued a post-hypnotic command to the entire human race instructing them to kill the Silence on sight. (DW: Day of the Moon) The Silence allied with Madame Kovarian, the Church and the Order of the Headless who were also behind the Battle of Demon's Run, as well as the kidnapping and brainwashing of the infant River Song - then known as Melody Pond. She then made several attempts on the Eleventh Doctor's life. Ultimately, she successfully introduced a poison into his system, a kiss on the lips with poison lipstick, which killed him. Though she later broke free of her conditioning and offered him the sum of her regenerative energy, saving him. (DW: Let's Kill Hitler).

The Silence, however, managed to track River Song down to the Luna University, where they kidnapped her and forced her into an astronaut suit as part of their plan to kill the Doctor. (DW: Closing Time). One of the Silence was present near Lake Silencio in Utah to observe the Doctor, River, Amy and Rory during the event of the Doctor's death. (DW: The Impossible Astronaut) Their plan was foiled, however, when the Doctor convinced the crew of the Teselecta to disguise their android as himself and take his place, tricking the Silence into believing that they had successfully killed the Doctor. (DW: The Wedding of River Song)