Empress of the Racnoss (The Runaway Bride)

The Empress of the Racnoss was the leader of the Racnoss Empire.

Biography
When the Racnoss empire was destroyed by the Gallifreyans over 4.6 billion years ago, the Empress was the only Racnoss to survive and not hibernate in the Earth's core. Instead, she thrived in her ship, the Webstar, orbiting Earth for billions of years until the Torchwood Institute developed Huon particles with which she could revive her race.

The Empress was encountered by the Doctor on Christmas Day 2007, in a secret location under the Thames Flood Barrier, trying to awaken her long-dead race, whom she called her children, with the Huon energy within the bodies of Donna Noble and Lance Bennett, who had been fed the energy through the medium of drinks, coffee and water respectively. Lance was originally affiliated with the Empress. However, following the disappearance of Donna after being taken by the Doctor, she sent Lance to the centre of the Earth where the Racnoss spaceship was. There the Huon particles awoke the Racnoss who then proceeded to feast on Lance.

Her plans to revive the Racnoss were foiled by the Doctor. He used controls stolen from a Robot Santa to stop the Santas shooting him and set bombs, disguised as baubles from a Robotic Christmas Tree, flying around the secret room. The bombs detonated, crashing into pipes, letting the Thames flood into the room, surrounding the Empress with fire, and finally drowning the Racnoss with the Thames water.

The Empress transmatted up to her Webstar and vowed revenge on the Doctor and all of planet Earth by scorching it. However, the lack of Huon energy left the Webstar defenceless, and allowed the British Army to destroy it, with the Empress. The order to destroy the Webstar came from Harold Saxon himself. (DW: The Runaway Bride)

Donna Noble would later tell Agatha Christie that her fiancee ran off with a "giant spider" in an attempt to comfort her, as her husband had cheated on her. (DW : The Unicorn and the Wasp)

Alternate timeline
In an alternate timeline, the encounter between the Doctor and the Empress ended differently. Although she was still killed, the Doctor also died, leading to a chain of events that drastically altered Earth history. (DW: Turn Left) The Empress of the Racnoss was one of the many aliens to appear in a flashback when Donna began remembering the Tenth Doctor on Christmas 2009. (DW: The End of Time)