The Zakatrons are a military race, obsessed with war. They have threatened the earth numerous times, and remain a very real danger to the planet.
Their first known attempted attack was in 2007, though this is only known through what Liam has revealed. Whatever took place, it resulted in the serious injury of Daniel Smith, which is why Liam was forced to make him a Cyborg in order to save him. How the Zakatrons were defeated on this occassion is unknown.
The second time the Zakatrons tried to invade was in 2009, when Liam was mostly absent from the team. This time, Dan the Cyborg was able to deactivate their ship and leave it floating through space before they could be captured.
The Zakatrons attacked again later that year, this time revealing a master plan to dig into the centre of the earth in order to obtain a weapon of mass destruction which is later revealed by Mortis to be a "Sun Destroyer". The key that should unlock the weapon, however, was blown up along with Ben Goodlad, and the Zakatrons left the earth once again.
Their latest attack on earth took place in 2010, and is known to the world in the aftermath as the "Katrina Mills Massacre". This time they attempted to use Dan the Cyborg, a being of both human and robotic aspects, to access the Sun Destroyer. However, their attempt was unsuccessful after Dan became human due to a shot to the back from a Zakatron. This irony led to their downfall, as the Dark Gods - creators of this weapon - took vengeance upon the Zakatrons for their feeble and unsuccessful attempt.