Skithra

The Skithra were a species of scorpion-like beings.

Biology
At least one individual, the Queen of the Skithra, had a partly humanoid appearance (TV: Nikola Tesla's Night of Terror) and resembled a Racnoss. (TV: The Runaway Bride) As a hive species, if the Queen was destroyed, the rest would also die.

The Skithra were able to fire an energy resembling electricity from their stingers. This energy would appear green when charging and would turn red when it was about to be fired. (TV: Nikola Tesla's Night of Terror)

Technology
The Skithra were scavengers who believed that they were superior to other races and therefore entitled to their technology. They would steal the technology of other races and use it for themselves rather than building their own. Races that the Skithra have stolen from include the Silurians, Thassor, Venusians, Klendov, and Dullirians. When the stolen technology started to break down, they would kidnap an engineer of another species and force them to repair it, regardless of whether or not they or their species were familiar with the technology. If the engineer could not repair the broken technology or refused to do so, the Skithra would kill them.

The Skithra had also at some point stolen technology which allowed them to appear human. This technology even allowed them to disguise themselves as specific individuals, and did not require the individual to be kept alive in order to keep their appearance. When disguised as humans, their red eyes were left undisguised and the energy which came from their stingers appeared to come from their hands. (TV: Nikola Tesla's Night of Terror)

History
In 1903, the Skithra Queen threatened the Earth with a stolen Venusian spaceship with a Klendov warp drive and a Dullirian resonator. At some point, they stole a Silurian blaster, presumably from one of the underground settlements the species hibernate in, which they used in an attempt to kidnap Nikola Tesla. (TV: Nikola Tesla's Night of Terror)

At some point, one Skithra was imprisoned in the same Judoon prison as the Thirteenth Doctor. (TV: Revolution of the Daleks)

Alternate timeline
In an alternate timeline created by a paradox caused by an encounter between the Thirteenth and Tenth Doctors in 1969, (COMIC: A Little Help from My Friends) the Skithra successfully kidnapped Thomas Edison and Nikola Tesla in 1903 and awoke a colony of Sea Devils in the Raven Peninsula. The Sea Devils took over Earth on the Skithra’s behalf, however by 2020 one Skithra Queen had turned against her people and was attempting to help the humans. She helped the Thirteenth Doctor and her friends escape a prison camp and travelled back in time with them to 1903 to correct the timeline. She killed the drone that had been sent to awaken the Sea Devils and worked with the Doctor to sabotsge the Skithra ship whilst the Tenth Doctor rescued Edison and Tesla. The present Queen attempted to stop her, but the future Queen fought her until the ship exploded. (COMIC: Alternating Current)