So in Legends pretty much no one knew who Vader actually was outside of Yoda, Kenobi and the Emperor. Tarkin and Thrawn both figured it out on their own.
Even in the new Disney timeline Vader's true identity is supposed to be known to very few people. Once again the Emperor, Tarkin and Thrawn with the last 2 figuring it out. Vader has been known in the new canon to kill people for specifically figuring it or even seeing his face.
But the new canon now is already so bloated and confusing that they're already contradicting themselves and it is only going to get worse with everything being full canon.
So in Legends pretty much no one knew who Vader actually was outside of Yoda, Kenobi and the Emperor. Tarkin and Thrawn both figured it out on their own.
Even in the new Disney timeline Vader's true identity is supposed to be known to very few people. Once again the Emperor, Tarkin and Thrawn with the last 2 figuring it out. Vader has been known in the new canon to kill people for specifically figuring it or even seeing his face.
But the new canon now is already so bloated and confusing that they're already contradicting themselves and it is only going to get worse with everything being full canon.
In the 2017 Vader comic he kills every Stormtrooper on a dropship after the Jedi they are trying to catch reveals Vader's identity to them.