The 'Lighter' Side Of The Force
Maybe Tarkin?He figured out Vader had been Anakin. If he knew just a little about Vader as a Sith, then the only conclusion is that the Emperor was Vader's Sith master.
well maybe it's not included because it's overly obvious (though you did list the obvious ones like Dooku, Vader, Kenobi and Yoda): Mace Windu and his team that confronted Palpatine in Ep III obviously knew. Perhaps not included because they died? But so did others in the list.
I assume Ashoka Tano knows since she finally confronted Anakin/Vader in Star Wars Rebels.