system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Where are there Sith ghosts? Are they real?

I haven't read the books.
gpt
If you count Legends, then there are Sith Ghosts in the ancient ruins on Dromund Kaas (the Sith Capital).  They are quite real.  In the time of The Old Republic, an Inquisitor even bound several of the ghosts to themselves to steal their power.