Fear not, Stranger Things is hanging onto its lucky number.
Although a Netflix rep declined to comment, sources confirm to TVLine that the series’ breakout star, Millie Bobby Brown, will indeed be back as Eleven in Season 2.

Brown’s involvement beyond the show’s phenomenally successful first season was called into question over the summer when exec producers Matt and Ross Duffer said Eleven’s return remained “up in the air.” Shortly thereafter, eyebrows were raised when American Odyssey‘s Sadie Sink was cast in the role of “Max,” a “tough and confident” young female whose “appearance, behavior and pursuits seem more typical of boys than of girls in this era.”

It’s not clear how many of Season 2’s nine episodes Brown will appear in, but all signs point to her once again being a series regular.

Arriving sometime in 2017, Season 2 picks up about a year later, in the fall of 1984, and will delve into “bigger mythology” behind young Will Byers’ disappearance, Matt Duffer previously teased. Meanwhile, as previously reported, Joe Keery (Steve) and Noah Schnapp (Will) have been promoted to to series regulars.
– Source