Racnoss

The Racnoss were an ancient race from the Dark Times of the universe who re-emerged after billions of years to threaten Earth in 2007.

Appearance
The Racnoss looked like large half-humanoid, half-arachnid beings, with blood-red skin and a crested skull. They had three pairs of eyes – one pair in the place where humans have theirs, and the remaining ones on the forehead. They had ten razor-tipped limbs, two of which were arms that strongly resembled blades. They had spinnerets at the base of their abdomen, allowing them to produce miles of webbing. (TV: The Runaway Bride)

Life cycle
Born with a ravenous hunger, the Racnoss mastered teleportation, which completely negated the need for them to land their ships when they visited other planets. The Empress apparently was the one who had the duty of laying eggs, which hatched into other Racnoss, meaning that the entire Racnoss race were the children of the Empress. The young were born starving, and so invaded planets to feed off all life on them. (TV: The Runaway Bride)

Technology
Most of Racnoss technology was made of a fine, silk-like substance, strengthened and powered by Huon energy, including their spacecraft, amongst other things.

The Webstar had energy weaponry which was used to kill for meat. It also had scanning equipment which the Empress of the Racnoss used to watch a planet and a teleporter to allow her to travel to and from the planet. (TV: The Runaway Bride)

History
The Racnoss evolved in the Dark Times of the universe. (TV: The Runaway Bride, The Infinite Quest) They had some form of civilisation on Arcnoy Twelve, which was in ruins by the 51st century. (PROSE: River of Time)

At some point in their history, the Racnoss were attacked by the Cybermen. (PROSE: Ghost in the Machine)

They were nearly wiped out by the Fledgling Empires (TV: The Runaway Bride) in the Racnoss Wars (AUDIO: Empire of the Racnoss) over 4.6 billion years BC. Gallifreyans also had a hand in this. Another source posited that the Racnoss ate each other to near extinction, at least according to the Matrix. (PROSE: Doctor Who and the Krikkitmen)

Nearly all of the survivors of the race escaped in their spacecraft, around which the planet Earth would later form. The Empress of the Racnoss stayed in her Webstar, but also went into hibernation at the edge of the universe until she decided to search for her young.

Around 2007, the Torchwood Institute began a drilling attempt to the centre of the Earth. This awoke the Secret Heart, which in turn signalled the Empress of the Racnoss. She came to Earth and used Huon particles manufactured from the River Thames to feed Donna Noble with the right catalysis of particles to awaken her young. The Doctor killed the Racnoss young by flooding the tunnel to the centre of the Earth with water from the Thames while the Empress teleported back to the Webstar plotting revenge. However, she had used up all of her power to attack London and revive her children and was left defenceless to a tank attack ordered by which destroyed the ship and killed her, rendering the Racnoss extinct. (TV: The Runaway Bride)

Alternate timelines
In an alternate timeline where Donna had not been there to help the Doctor, the Doctor flooded the tunnel to defeat the Racnoss, but at the expense of his own life. The tank attack still destroyed the Webstar. Due to the Doctor's death, however, he was not present for following catastrophes he prevented in the original timeline. With the help of Rose Tyler and UNIT, Donna was able to travel back in time and negate this timeline. (TV: Turn Left)

Other references
The Jagaroth came to Earth tracking a Racnoss energy signal, (PROSE: City of Death) four hundred million years prior to the 20th century. (TV: City of Death)

Some historians believed that a splinter nest of Racnoss may have been the ones that attacked the makers of the Clades. (PROSE: Peacemaker)

When Donna Noble's hands were changed into claws, she complained that she felt "Racnossy". (COMIC: The Continuity Cap)

Jack Harkness, recalling something that the Doctor told him, speculated that an interaction with the Racnoss hibernation field's huon particles may have resulted in the Blessing, but was forced to admit he had no idea. (TV: The Blood Line)

A drawing of a Racnoss was inside the clock tower in the town of Christmas during the Siege of Trenzalore. (TV: The Time of the Doctor)

Behind the scenes

 * Before Series 12 episode Nikola Tesla's Night of Terror aired, it was widely believed that the Racnoss would return given the uncanny resemblance between the Empress and another species', known as the Skithra, Queen of the Skithra.