The primordial Goa'uld of P3X-888 were predators that evolved for millions of years in the prehistoric oceans. Snake-like vertebrates with blue blood, this early species had wing-like appendages, allowing them to leap over distances, and naquadah did not become a part of their physical makeup until later in their evolution. Eventually, they learned to take the indigenous aboriginal Unas as hosts whom they could control. Those who took hosts learned to use the stargate and left the planet, becoming a parasitic race of conquerors. Goa'uld larvae are produced by queens, such as Hathor, who use the DNA from the intended host species to ensure compatibility. Symbiote queens produce large egg sacs and are able to fertilize their own eggs, thus reproduction is essentially an asexual process. Goa'uld offspring are born evil, with the genetic memory and the intellect and collective knowledge of their lineage which is passed on voluntarily by the queen who bore them.

Replicators were the enemy of the Asgard. A sophisticated but childlike android constructed them as toys using nano-technology to reorder matter on a microscopic level. She could control them with her mind, but as she taught her toys to replicate and to protect her, she began to lose control. The Replicators destroyed everyone on her homeworld, then spread through the stargate to other planets.Replicators appeared as mechanical spiders and had an extremely high capacity for learning, with the ability to incorporate or modify the technology they consumed. They were a kiron-based technology, a kiron being an energy particle unknown to Earth technology. Each individual building block was capable of exerting a reactive modulating mono-polar energy field on other blocks, allowing them to assemble themselves into many forms, in order to perform various tasks, both individually and as a group, ultimately for the single purpose of self replication.

Both the Ancients and the Ori evolved from a race known as the Alterans. Millennia ago, in a distant galaxy, the Alterans were a human society on an evolutionary path to ascension. However, a philosophical division grew, and those who became more and more fervent in their religious beliefs tried to wipe out the others of their race. Those who recognized the potential abusive corruption of these religious beliefs favored science instead and believed absolutely in free will. Rather than go to war, these Alterans built a ship, left their galaxy behind, and came to the Milky Way where they eventually ascended and came to be known as the Ancients. Those they left behind were known as the Ori. They too learned to ascend, and they passed down a religion called Origin to the next evolution of humans they created.As ascended beings, the Ori have evolved physically and mentally to the point that they have found a way to shed their physical bodies and live as energy.