3. Darth Bane
Okay, let’s not split hairs between “Force Ghosts” and “Sith Ghosts.” Both the Jedi and Sith are manifestations of the Force. Plus, Darth Bane has already appeared in canon, to Yoda in the aforementioned Clones Wars Season 6. The current Star Wars comic run has also established the possibility of the Sith communicating from the beyond. Is it really that much of a stretch to have an ancient Sith commune with Kylo Ren?
2. Obi-Wan Kenobi
Despite more rumors than we can count centered on an Obi-Wan Kenobi film/series, we’ve yet to hear anything about Ewan McGregor returning to Star Wars in Episode IX. That’s too bad. Rey will (presumably) continue her training on her own with the sacred Jedi texts. Now she has no living guidance in the Force. Remember, however, that she heard Obi-Wan’s voice during her first vision in The Force Awakens. How awesome would it be for Kenobi to pay her a visit in Force Ghost form?
And number 1…