|Location||Originally - Hell, since 2.22 - "the west" of the USA|
|Episode(s)||3.12 Jus in Bello|
Lilith is Sam's demonic rival.
The demon Lilith is one of the most infamous in demonology.
In Supernatural, she is first referred to - though not by name - in 3.09 Malleus Maleficarum when Ruby warns him of a rival "in the west".
In 3.12, Ruby accounts the demon hoard to Lilith. At the end of the episode Lilith shows up looking for Sam & Dean before destroying the sheriff's office (and its occupants).