The Daleks are alien mutants who originated on the distant planet Skarro who encase themselves in cylinder-shaped, mobile body armor, equipped with anti-gravity transportation, force fields, and energy weapons, They also have fleets of flying saucers capable of faster-than-light drive. They try to dominate non-Dalek races or otherwise exterminate them.
They Cybermen are alien, cybernetic, semi-robotic humanoids from an unknown world who try to convert humanoids (including possibly the humans of Earth) into new Cybermen. They also have energy weapons and interstellar-capable spaceships.
Both Daleks and Cybermen are a serious threat to the security of the planet Earth.