4. The Axons
Last seen in 1971, the Axons, looking for fuel, landed on Earth, intent on draining the energy from life forms on Earth, and their dastardly plot is seen in the case of Jo Grant, who begins to age, as the Axons drain energy from her. Ultimately the Doctor stops them from spreading their ways of feeding on life forms through time and space by putting them in a time loop. The Axons are a popular enemy among the fanbase, and just recently Character Options released a photo for a new action figure set featuring Jo Grant, the Brigadier and the Axon, so now all that is needed is the Axons back onscreen for the new series.
3. The Rutans
The only time the Rutan has appeared in Doctor Who onscreen is in Horror of Fang Rock. It is a green blob with tentacles,that will kill an individual, and then impersonate said individual.A compelling and somewhat familiar villainous trait, and with the effects the series uses today, they could certainly make the Rutan look a bit more intimidating.