The two candidates were Special Child Sam Winchester and Lilith, the latter who had been released from the depths of Hell when the Devil's Gate was opened. As Sam had no intention of leading the demon army, Lilith took over and declared herself the new ruler of Hell.
On Lilith's orders, the demons set about eradicating Lilith's competitor Sam. Secretly, Lilith also sent Ruby to ally herself with Sam so that he could be prepared for his ultimate fate of killing Lilith as the final seal to Lucifer's Cage, leading to the beginning of The Apocalypse. The first seal was Dean Winchester, who was to torture souls in Hell.
Lilith's demons are first shown attacking Monument, Colorado police station where Sam and Dean are held. Ruby offers to assist the brothers in destroying the demons by creating a bomb that will kill every demon in a certain radius, but at the cost of Nancy Fitzgerald. Sam and Dean decline her help and using their own tactics, they are able to find off the demons inside and outside the police station. The fight ends with Lilith, in the body of a young girl, arriving at the police station to personally kill the survivors, save for Sam and Dean. 
Lilith's demons appear again at New Harmony, Indiana, taking possession of the local townsfolk while Lilith poses as the daughter of the Fremont Family. Sam and Dean arrive at the neighborhood in hopes of confronting Lilith and freeing Dean of his Crossroad deal. The pair manage to fend off the demons guarding the Fremont house, but fail to kill Lilith when she secretly takes possession of Ruby's blonde vessel. Lilith sics the hellhounds on Dean thus dragging his soul to Hell. Lilith attempts to kill Sam but fails.
During the four months in which Dean is being tortured by Alastair so that he may torture souls himself, Lilith sends Ruby to be with Sam to manipulate him into following his destiny. She also sends a couple of other demons to fight the pair so that Sam grows to trust Ruby more. No one but Lilith and Ruby are aware of Ruby's true alliance.
Once Dean breaks the first seal, Lilith begins sending demons out to break the remaining 64 seals. Among the demons sent out is Alastair. Sam, Ruby and a newly-resurrected Dean try to fight against the demons and protect the seals. On Heaven's orders, an army of angels are also sent to protect the seals, although their true intentions are to allow The Apocalypse to begin.
Once 65 seals have been broken, Lilith, in the body of a young woman, awaits a fully manipulated Sam to arrive at St. Mary's Convent, the location of the doorway to Lucifer's Cage. An Entourage of demons guard the entrance while one expresses sorrow at Lilith's coming demise. Sam, empowered by the consumption of demon blood, kills the demons and proceeds to kill Lilith, thinking by that doing so, he is preventing the final seal from being broken.
Upon Lilith's death, Lucifer's Cage is opened and Lucifer springs forth. What remains of Lilith's followers move on to follow Lucifer, with the exception of Ruby (who was killed shortly after by Dean) and Crowley, who defected to join the Winchester brothers.
- Alastair (deceased)
- Astaroth (deceased)
- Claire's captors (deceased)
- Amelia Novak demon (exorcised)
- Cindy McKellan's demon (deceased)
- Captive Demon (exorcised)
- Cop Demon (deceased)
- Crowley (deceased) (formerly)
- Deputy Demon (unknown)
- Jeffrey's Demon (exorcised) (formerly)
- FBI Demon (exorcised)
- Siege Demons (deceased)
- Lilith's Assassins (two deceased, one exorcised)
- Lilith's Entourage (deceased)
- Merrick (unknown)
- Ruby (deceased)
- Siege Demons (deceased)
- For a short time, Bela Talbot had joined Lilith's side in hopes of being set free from her own crossroad deal. Her failure to kill Sam and Dean ended their alliance.