- "He who wields the blade will be able to control my brother."
- ―The Daughter
The Dagger of Mortis, also known as the Mortis Dagger, was a blade that was kept in the underground Altar of Mortis. It was capable of killing the Ones; namely the Father, Son, Daughter, and Mother/Abeloth.
During the Clone Wars, Jedi Master Obi-Wan Kenobi and Jedi Knight Anakin Skywalker attempted to use the Dagger of Mortis to kill the Son, but when the Son stole it and tried to kill the Father with it, the Daughter sacrificed herself to protect her father. The Father placed it with the Daughter's body in her tomb, but the dagger was stolen by the Son shortly thereafter. Rather than have the Son murder him with it, the Father took it from him and stabbed himself with the blade, mortally injuring himself and severing the Son's powers, allowing him to be killed by Skywalker.
After the death of Abeloth, the former Mother, in 44 ABY, Grand Master Luke Skywalker sent ten Jedi Knights out to search for the Mortis monolith so that they could recover the Dagger. The Jedi wanted the Dagger as insurance against the return of Abeloth. The Son and the Daughter were the ones who had defeated Abeloth every time she had escaped before, and since the Dagger could kill the Ones, Luke believed it could also kill Abeloth—who had drunk from the Font of Power like the Son and bathed in the Pool of Knowledge like the Daughter. It is unknown whether the Dagger was created on Mortis, or the Ones' original home planet.
- Star Wars: The Clone Wars – "Altar of Mortis" (First appearance)
- Star Wars: The Clone Wars – "Ghosts of Mortis"
- Fate of the Jedi: Apocalypse (Mentioned only) (as "Force-imbued dagger")
- (First identified as Dagger of Mortis)
- (First identified as Mortis Dagger)
- Star Wars: The Clone Wars Magazine 5
- Star Wars: The Ultimate Visual Guide: Updated and Expanded
- The Essential Reader's Companion
- "100 and Counting"—Star Wars Insider 139