Gallius Rax — born Galli, an orphan on the desert world of Jakku, and code-named the Operator — is the hidden architect of the Empire's end. He is introduced in Chuck Wendig's Aftermath (Del Rey, 2015) and his role becomes explicit across Life Debt and Empire's End.
The Contingency
Palpatine's final instruction was not a plan to preserve the Empire. It was a sentence passed on it: if the Emperor died, the institution that failed to protect him was to be dismantled, its worlds burned in Operation Cinder, its fleet drawn to one place and destroyed, and a small selected remnant sent into the Unknown Regions to begin again. Rax holds the title Counselor to the Empire, a regency invented for him, and executes the whole thing while the Moffs believe they are rallying.
Jakku
He brings the surviving Imperial Military to his own homeworld and starts the battle that ends the war. Grand Admiral Rae Sloane works out what he is doing partway through, which sets up the confrontation the trilogy is actually built around: two Imperial officers arguing over whether the Empire deserves to survive, while a hundred thousand people die around them for reasons neither side has been told.
The reveal, and the reservations
Rax is a divisive piece of retroactive plotting. He explains a great deal — why the Empire mustered at a worthless desert planet, why the First Order exists, why the Unknown Regions matter — and he does it by inserting a previously unmentioned figure at the centre of events. Readers who dislike the Aftermath trilogy usually name him first; readers who defend it point out that a secret regent is exactly the kind of thing Palpatine would have arranged and told nobody about.
