The Cheetah People
The Cheetah People, who first appeared in Rona Munro's Survival, appear in a whole season in early 2010. They usually exist because of Ace passing on the Cheetah Virus which she became infected with.
The Graske first appeared in the new series interactive episode Attack of the Graske and reappeared in two Sarah Jane Adventures stories. He also appeared in Music of the Spheres, and is returning in the 2010 audio The Graske Chase.
The aliens the Squeakakas try to conquer the Earth, but they need help. So, they begin playing Halo 3 to increase the fitness of their armies, but they are complete n00bs at it. So, they make robots of Halo characters, but given them Human brains and testicles. When the Doctor and Ace arrive at an arcade in 1991, playing Machinima's I Bagged a Noob on her phone, their brain overwrites their data and they begin teabagging all pros and infect them with AIDs. The only way to stop them is to infect them with the Cheetah Virus. They later overthrow the land of fiction and populate it with Halo characters.
The Slyther was part of the Dalek Invasion Force, but it got lost and landed beneath Starbucks in 1996. It recreated the Dalek armies but the Seventh Doctor managed to defeat them by deflating the mutant creature. He then sent the Slyther back to 2157 - only to land in the River Cam in Cambridge. It was discovered by Luke Gibbon, and 2 years later, it launched an attack on Taverham. The Doctor killed it, but had to clone it because it needed to attack Ian in c2164.
The Daleks were created by Davros, and they located him in 2159, and was sentenced to execution, but managed to stop them by reflecting their laser beam back on a mirror he got from his Granddaughter Susan English Foreman.
Robomen were once humans, but the Daleks turned them into robotic slaves and used them during the Dalek Invasion of Earth. The Doctor managed to defeat some by using a karate chop, which managed to cut off their electronic signal.
Jason was a teenage boy, who became the second master of the Land of Fiction. He faced trial from the Time Lords after the Doctor played a game of Chess with the Celestia Toymaker.
The Celestial Toymaker first appeared in an episode in 1965, and reapeared in the audio Return to the Land of Fiction, where he had struck a deal with Jason to help him kill the Doctor. He played a game of Chess with the Eighth Doctor, but he managed to take his king, and sent him back to his toyroom, awaiting the Seventh Doctor's arrival... In a future episode, he brings Star Wars action figures to life.
Dr. Who was a fictional double of the Seventh Doctor, created by Jason. The Eighth Doctor managed to exile him to Earth in a new body, who had already stolen the TARDIS instructions, and, thinking he was a human inventor, he managed to build himself his own time macine.
Having gotten trapped in the Eye of Harmony, the Doctor's companion Olivia was able to let him escape by looking in to the light, but the Doctor managed to get him back in using his Sonic Screwdriver. Little did he know that he was about to launch a secret trap on the Doctor. Back in a previous life, he managed to take an underground train through a Time Tunnel, leaving the Time Lord Jackunakunalundar (Jax for short) hostage, but the Fourth Doctor and Sarah Jane managed to get him back to Gallifrey. He also trapped the Tenth Doctor in a YouTube, with the only means of escape being in the Mushroom Kingdom...
The Cybermen were heading for Antarctica, but they crashed into the UNIT headquarters accidently. The Doctor managed to fix their ship and get them to Antarctica, only to later find out they later crashed into a Ski resort in Alaska. Parrelal versions of Cybermen attacked the Doctor and Martha on the planet Centuria.
The Sontarans are a race of humanoids with a stocky build, greenish brown skin, and a distinctive dome-shaped head. The Sontarans have an extremely militaristic culture; every aspect of their society is geared toward warfare, and every experience is viewed in terms of its martial relevance. The Sontarans reproduce by means of cloning rather than sexual reproduction, and thus for the most part are extremely similar in appearance. In both the classic and new series, Sontarans are depicted using spherical or semi-spherical single-occupant spacecraft.
race of reptile-like humanoids that went into self-induced hibernation to survive what they predicted to be a large geological upheaval caused by the Earth capturing the Moon. The Silurians introduced in the 1970 story are broad, three-eyed land-dwellers. The 1972 serial The Sea Devils introduced their amphibious cousins, the so-called 'Sea Devils'. The 2010 episode "The Hungry Earth" introduced another more human-like branch of the species.
Judoon are galactic police, brutal in their precise application of the law and highly logical in their battle tactics, but not very intelligent. They first appeared in the 3rd series since the revival, originally encountered by the tenth doctor. The Judoon carry energy weapons which can incinerate humans. The name 'Judoon', and the fact that the episode they appear in is set on the Moon, is an in-joke from the scriptwriter.
Whilst the Ood initially appear as a slave race who become hostile, over the course of the stories they are shown to be a naturally peaceful race, and by The End of Time have progressed to becoming an advanced civilization. The Ood are humanoid in appearance with tentacles on the lower portions of their faces. They require a translator device, a small sphere connected to their "mouths" by a tube, to facilitate speech between them and humans, as they do not have vocal cords.
According to the Doctor, the Weeping Angels "are as old as the universe (or very nearly), but no one really knows where they come from." He also describes them as the loneliest beings in the universe, since their quantum-lock reaction makes it difficult for them to socialize. The weeping angels appear to be nothing more than statues of angels. However, when you look away, they move.
Autons are essentially life-sized plastic dummies, automatons animated by the Nestene Consciousness, an extraterrestrial, disembodied gestalt intelligence which first arrived on Earth in hollow plastic meteorites.
They are creatures of living calcium, hatched from eggs and native to the planet Raxacoricofallapatorius. Though the name "Slitheen" refers to a specific family, the term has been used by the Doctor and Rose to refer to the Raxacoricofallapatorian race in general. The Slitheen are a ruthless criminal sect whose main motivation is profit. They are instinctive hunters, being trained to hunt and kill from a young age.
these creatures have large heads and long fingers. The Silences most notable feature is that you can only remember them while you're looking at them. When you look away, you lose all memories of what they look like and forget you even saw them. You can remember all encounters when you see them. They also have the power of post-hypnotic suggestion. The Doctor uses this to his advantage in Day of the Moon. He and his companions traveled to 1969, the year of the moon landing. They discovered the Silents, and tricked them into giving mankind the order to kill them all on site. However, the are first seem by Amy Pond in 2011. They will reappear at the end of series 6.
The Cybermen also use smaller, cybernetic creatures called "cybermats" as weapons of attack. The Cybermats appeared in "Blood of the Cybermen" where instead of killing, they turned individuals into cyberslaves. The Cybermats are due to make a return, in a redesigned form, in the autumn episodes of the 2011 season of Doctor Who facing Matt Smith in his second year in the role.