Dahak is the source of ultimate evil
from the third season of Xena, Warrior Princess
, whose only goal is complete world destruction
. He is a god
, but he is not an Olympian
; rather he leads an independent cult
that pretends to worship
the One-God of the Israelites
. Under this guise
, the daemon followers
of Dahak convince Xena
to protect their temple
from the Romans
It is in the temple of Dahak that Gabrielle is forced to take her first human life (or "lose her blood-innocence", as she put it herself). Her innocence lost, Gabrielle becomes vulnerable to Dahak, who takes her into his flame and impregnates her with his own evil seed, who will become, in essence, the Antichrist.
When Gabrielle gives birth to her new daughter, whom she ironically calls Hope, she is taken by an internal conflict between her love as a mother and the need to prevent world destruction. She chooses to save Hope from the prudent wrath of Xena, but Hope indeed grows to spread the evil "gospel" of her father throughout the world. Finally, after Hope murders Xena's son, Solon, Gabrielle kills her with poison.
However, the cult of Dahak soon returns with the help of Ares and Callisto; and Hope is revived in a cocoon, from which she emerges looking identical to Gabrielle. Among Dahak's brainwashed followers, Gabrielle is known as "the betrayer," and the new Hope is believed to harbinger a golden age of peace and purity. Of course, by purity they mean complete purgation of the human race. Gabrielle throws herself and Hope into Dahak's fire pit in an effort to kill her and save Xena(this is only the first death of Gabrielle in a series of many).
Defeated in Greece, Dahak then moves to Mesopotamia, where he tricks Hercules into killing the Sumerian gods and then slays Iolaus. He then follows Hercules back to Greece and possesses Iolaus's body for a second attempt at the Olympians. Dahak is finally exorcized from Iolaus and killed by Hercules in a metaphysical spirit world. It is here that the force of Dahak is finally replaced by the still darker force of Satan.