Characters in Star Wars Episode IX - The Rise of Skywalker

Rey

Also in Star Wars: The Last Jedi, Shadow of the Sith

Finn

Poe Dameron

Also in Star Wars Episode VII - The Force Awakens

Emperor Palpatine

Also in Star Wars Episode III - Revenge of the Sith, Star Wars Episode VII - The Force Awakens, From a Certain Point of View, Shadow of the Sith, Star Wars - Lords of the Sith, Star Wars - Queen's Hope, Star Wars - Tarkin, Thrawn, Thrawn: Alliances

Kylo Ren

Also in Star Wars Episode VII - The Force Awakens, Bloodline, Empire's End

Darth Vader

Also in Star Wars Episode V - The Empire Strikes Back, Star Wars Episode VI - The Return of the Jedi, Star Wars Episode VII - The Force Awakens, Doctor Aphra, Star Wars - Bloodline, Star Wars - Jedi Battle Scars, Star Wars - Lords of the Sith, Star Wars - Tarkin, Thrawn, Thrawn: Alliances