The who is Marrok in Ahsoka debate has been raging ever since the mysterious Inquisitor looking character showed up in promotional materials, and while many fans, including us have guessed that they will be Barris, or Dark Ezra, or Starkiller, the actual reveal may be a bit disappointing and not as lore rich as you’d like.
SPOILERS
I’m running this as a rumor because I couldn’t vet it with an additional source, but it is sounding like Marrok will indeed just end up being a slightly older version of the Eighth Brother from Star Wars Rebels.
I want to give credit to our fan Super_Scoundrel, who has been trying to convince us that Marrok would be the Eighth Brother all along even though the guy we see in Ahsoka has five digits on his hand while the 8th Brother did not, and he was also supposed to be dead, but here we are.
Hopefully the fingers will be explained, because his race can have a full suite of digits, but as you will see below, he only had three fingers in Rebels, but now he seems to have a full set.

The armor is undeniably similar, so there’s that, but according to the one source I ran this stuff over with, Marrok will indeed just be the Eighth Brother.
Nick and I will talk more about Marrok the 8th on next week’s episode of the SWTS, so don’t forget to tune into the Star Wars Time Show on a weekly basis via our podcast platforms or via YouTube if you prefer the livestream angle.