We know that Kylo Ren is Supreme Leader Snoke's apprentice, but recently I was wondering: Did Snoke have any other apprentices before Kylo Ren?
Snoke has had at least one other, and potentially several other apprentices over the years.
The Star Wars Insider Last Jedi: Special Collector's edition contains the following cryptic note
"Force sensitive, and highly attuned to the dark tide but not a Sith, Snoke has trained Kylo Ren and least one other apprentice."
And the Visual Dictionary for The Force Awakens states that Kylo Ren is the most gifted of (presumably) several apprentices.
"Kylo Ren is the most gifted apprentice of Supreme Leader Snoke, a mysterious figure steeped in dark side knowledge who commands the First Order from a distance."