- "He who wields the blade will be able to control my brother."
- ―The Daughter
The Dagger of Mortis, simply referred to as the Mortis Dagger, was a mystical weapon that resided on the Altar of the Wild Space world of Mortis. The weapon was kept hidden on the realm of Mortis by the Father, who kept it as a means that could control his children, the Daughter and the Son. The weapon was capable of controlling the sibling pair of powerful Force wielders, and it was also capable of killing them, if necessary. When used on the Father, however, his death at the hands of the dagger would rob his children of their immortality.
When the Father learned that the Chosen One, a prophesied Jedi legend, had appeared in the galaxy, he lured the Jedi Knight Anakin Skywalker, believed to be the Chosen One, to his realm on Mortis. However, despite passing the Father's test to prove himself as the Chosen One, Skywalker refused to remain on Mortis in the Father's place, who was dying. The Son then attempted to lure Skywalker to the dark side of the Force, forcing the Daughter and Obi-Wan Kenobi, Skywalker's former Jedi Master, to retrieve the dagger from the Altar of Mortis in an effort to gain control over the Son.
The Son, however, was able to take the dagger from the Jedi, killing Skywalker's Padawan, Ahsoka Tano. When the Son attempted to kill the Father next, the Daughter intervened and was instead killed. A distraught Son left the dagger behind, and the Daughter's remaining life force was used to resurrect Tano. In a final effort to stop the Son, the Father used the dagger on himself, robbing the Son of his immortality and allowing Skywalker to deliver a mortal wound with his lightsaber. The act brought balance in the Force back to Mortis, and the dagger, along with the entire planet, disappeared in a blinding white light from the Father's monastery.
- Star Wars: The Clone Wars – "Altar of Mortis" (First appearance)
- Star Wars: The Clone Wars – "Ghosts of Mortis"