Vinvocci

The Vinvocci were a species of green skinned, spiky humanoids.

Biology
The Vinvocci were green, spiky humanoids. They resembled the Zocci, but were taller and green. (DW: The End of Time)

Technology
The Vinvocci had a medical device, dubbed the Immortality Gate by Humans, which was capable of healing "whole planets".

Rossiter and Addams used shimmers to appear as Humans. These devices, disguised as a wristwatch, allowed Rossiter and Addams to work for Joshua Naismith undetected. However the device was uncomfortable to use.

Rossiter and Addams also had a salvage spaceship. It had a teleport system connected to the wristwatches and several sets of automatated laser weapons for destroying asteroids. (DW: The End of Time)

History
In December 2009, a salvage team, consisting of Rossiter and Addams, arrived on Earth in order to find the Immortality Gate. The Gate had been reactivated by humans, and sent out a signal which attracted the pair. They infiltrated the company of Joshua Naismith, under the guise of two Human scientists. They were trying to repair the Immortality Gate, but the Master stopped their plans by using it to transform every human on Earth into duplicates of himself. The Vinvocci, unaffected due to their alien nature, helped the Doctor and Wilfred Mott escape the Master, bringing them to their ship. They later helped the Doctor return to the Naismith mansion, dropping off Wilfred shortly after. They then departed, unwilling to involve themselves any further in the conflict.

Apparently the words "cactus" and "cacti" -- references to an Earth plant of similar appearance -- are considered racist terms by the Vinvocci, as Rossiter indicated when the Doctor used the latter term. (DW: The End of Time)

Behind the scenes

 * According to the episode commentary, the original makeup design for the Vinvocci was not completely green. After principal photography had finished, Russell T Davies reconsidered the creatures' design and decided to have the footage digitally recoloured.
 * Russell T Davies suggests the Vinvocci and Zocci might be related species. (CON: Lords and Masters)