Atraxi

The Atraxi were a group of Galactic Policemen.

Appearance
The Atraxi resembled giant eyeballs who were connected to the bottom of their crystal/shard-like spaceships. The eyeball could also perform scanning tasks in a 'searchlight' fashion

Prisoner Zero
Whilst searching for Prisoner Zero they threatened to incinerate the Earth unless they found Prisoner Zero. In the process of this they sealed Earth within a force field so they could 'boil' the planet in 20 minutes.

The Doctor created a computer virus/message and got Jeff and team of geniuses to send the message worldwide on everything to give the Atraxi a hint where Prisoner Zero was, leading through to a mobile phone that the Doctor had. When the Doctor located Prisoner Zero in its natural form he lead the Atraxi to it whereupon they constrained Prisoner Zero.

Violation of Shadow Proclamation
The Doctor summonded the Atraxi back to Earth following their collection of Prisoner Zero for violoation of Article 57 of the Shadow Proclamation for threatening to incinerate the Earth. The Atraxi were challenged by the Doctor stating that Earth was "protected" through this the Atraxi viewed several races and species that had invaded or assaulted the Earth and its inhabitants, it also viewed various incarnations of the Doctor who had defended against these incursions, following this the Atraxi departed, swiftly. (DW: The Eleventh Hour)