Syll Nenn was a female Umbaran who was the twin-sister of Nyss Nenn. The siblings appeared to be Force-dead to other Force-sensitives, and while they weren't able to necessarily access the Force, they had a power that allowed them to dampen the abilities of Force-sensitives and also cloak themselves in it.
In 41 ABY, Syll and her brother were sent by Darth Wyyrlok to retrieve Jaden Korr and his clone, the Prime. The siblings had chased their targets throughout the Unknown Regions; an enterprise that ultimately saw to Syll's premature end when, upon firing on an escape pod containing Khedryn Faal, one of the lasers she fired was redirected by Korr, who used his lightsaber. The blast that hit the Nenns' ship head-on killed Syll when she was thrown into a wall by the blast. Nyss would go on to try to fulfill the mission, only to end up dead by Korr's hand as well.
- Riptide (First appearance)
- The Essential Reader's Companion (First identified as Syll Nenn)