Her roots apparently stem from the Babylonian Lilit (“maid of desolation”), as well as the Sumerian lil (“wind”). Some believe her name was confused with laylah, the Hebrew word for night.*
In popular etymology up to the 19th century, Lilith refers to “she who sucks blood in the night” (i.e. as a ghost or vampire). Lilith has also been called “the strangler of children.”
As the consort of the chief demon Sammael (the Jewish term for Satan after 200 CE), she’s “the Queen of all demons.”
In Kabbalistic literature, Lilith appears in men’s dreams as a seducer. Protective amulets were used against her. The owl was sacred to her. Depicted in the Talmud with a woman’s face, long hair and wings, some say Isaiah 34:14 indicates her presence in the Old Testament.
From Palestine her cult spread to Greece, where she merged with Hekate. Recently she’s been regarded as a symbol of inspiration and autonomy for women, as evidenced in the Jewish feminist magazine Lilith, first published in 1976.
* Like a lot of ancient material, there is much debate and ambiguity here.