*The MCU Fantastic Four movie may be setting up all the pieces to bring in Doctor Doom and Mephisto*
We'll dig into Shalla-Bal's comic book history to offer some insight into who she is, what her place in the Marvel Universe has traditionally been, and how that could potentially impact the MCU - as well as her own time as the Silver Surfer in comics.
Shalla-Bal's comic book story is inextricably tied to that of Norrin Radd, the classic Silver Surfer. As told in 1968's Silver Surfer 1 by Stan Lee and John Buscema, where Shalla-Bal first appears, both she and Norrin were residents of the planet Zenn-La. But their world is shaken (literally) when the planet-eating cosmic being known as Galactus appears over Zenn-La with plans to consume it as his next meal.
With few options and no weapons capable of deterring Galactus, Norrin makes a heroic sacrifice, offering to serve Galactus as his herald, seeking out suitable worlds for him to devour as long as Zenn-La - and Shalla-Bal - were spared. Agreeing, Galactus imbues Norrin with the so-called 'Power Cosmic' and turns him into the Silver Surfer.
Norrin leaves Zenn-La, and Shalla-Bal, never to return (or so he believes), eventually leading Galactus to Earth. There, the Surfer defies Galactus and is trapped on Earth as a result.