Empress of the Racnoss (The Runaway Bride)

The Empress of the Racnoss was the leader of the Racnoss Empire, an empire destroyed by the Gallifreyans over 4.6 billion years ago. She was the only Racnoss to survive and not hibernate in the Earth's core, but instead 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.

Encounter with the Tenth Doctor
The Empress was encountered by the Doctor on Christmas Day 2007 in a secret location under the Thames barrier, trying to awaken her long-dead race (who she called "[her] childern") with the Huon energy within the bodies of Donna Noble and Lance Bennet after being fed it within drinks, being given coffee and water respectively. Lance was originally affiliated with the Empress, however after the disappearence of Donna after being taken by the Doctor she sent Lance to the centre of the Earth where the Racnoss spaceship was, and thw Huon particles awoke the Racnoss and the Racnoss feasted on Lance.