From another galaxy, the Malecathi were once a people who formed an alliance with the most advanced Ancients until something did not break the alliance and make malecathi extremely dangerous. In this regard there are several hypotheses, including a 'global exposure level of a device similar to the "fountain of youth" which meant that the instincts were fully dormant in Malecathi to light. Defeated the Ancients, also thanks to shared technology, the Malecathi remained confined in their galaxy, and only recently made a foray into the Milky Way, in a time of great instability due to the fall of the Goa'uld .
Their acts of war have been achieved in different solar systems of the System Lords, destroying cities, entire populations and ecosystems in order to exterminate the race, the Goa'uld and the Earth's sentient. They are currently focusing on the Goa'uld Atlas, destroying one ship after another. Malecathi of you know the fact that they feel no pity for the vanquished, but not for their wounded.