Arcturan

Arcturans were a species from the planet Arcturus. They resembled humanoid skulls with tendrils.

Technology
In order to survive off their own planet, the Arcturans required life support systems. The most vital system was the helium regenerator. (TV: The Curse of Peladon) These systems would range from simple boxes with a necessary equipment to advanced systems capable of travelling and surviving nearly anywhere. (PROSE: The Doctor Trap)

During their invasion of Earth, Arcturans used Arcturan grenades. (PROSE: Combat Magicks)

Culture
Though the Arcturans knew of the Doctor, records of him were scarce. (PROSE: The Doctor Trap) They were known for being profit-obsessed and self-serving. (PROSE: Interference - Book One) The Arcturans were also known to make tea. (PROSE: Lucifer Rising) During the early 23rd century, the Arcturans were willing but suspicious traders with humans. (PROSE: The Janus Conjunction) Their language was called Arcturan. (AUDIO: The Bride of Peladon)

History
The Arcturans invaded Earth sometime before 451 AD, but were repelled. The Legion of Smoke acquired some Arcturan grenades from them. (PROSE: Combat Magicks)

The Arcturan Treaty of 2085 was once said to be the first official instrument of peaceful contact between humanity and aliens. (PROSE: The Dying Days)

By the 2210s, the Arcturans were trading goods with humans. Gustav Zemler thought that they "watched the humans carefully during negotiations, as an adult might watch a child". This was because humans had only recently gained space travel technology. (PROSE: The Janus Conjunction)

At some point after the Ice Warriors settled Cluut-ett-Pictar, the planet was attacked by an Arcturan strike-force. (PROSE: GodEngine)

In 3885, Peladon was attempting entry into the Galactic Federation. In the original timeline, the Arcturan delegate Arcturus killed Alpha Centauri and blamed the Ice Warriors, sending the Federation into chaos. (PROSE: Legacy) The Time Lords intervened and sent in the Third Doctor, who was chosen as the target and saved by Ssorg. (TV: The Curse of Peladon)

Undated events
The Semblance of Draxyx was an Arcturan and a member of the Endangered Dangerous Species Society. He was one of the members who arrived and was killed on Planet 1. (PROSE: The Doctor Trap)

The Tenth Doctor once reminisced about the time he, Rose Tyler and an Arcturan shared an experience in a cellar. (AUDIO: The Day of the Troll)

The Doctor once claimed to have won the Arcturan outer cluster in a game of inter-dimensional Buckaroo. (AUDIO: The Beautiful People)