The Netflix show’s cast eagerly watched the teaser for the first time alongside fans as it was premiered at Comic-Con San Diego on Saturday.
Eleven, played by Millie Bobby Brown, gave herself up for Will Byers in the climax of the first series.
But the final scene triggered hope that she would return after police chief Jim Hopper left her favourite treat, Eggos, in the woods.
Fans can rest assured that she will be back in the much-anticipated second season, which is due out shortly before Halloween.
The trailer, which was met by mass applause, saw Eleven prowling the alternate universe known as the Upside Down before she shoved an arm through a portal.
British actress Brown was joined by Finn Wolfhard, who plays Mike Wheeler, Dustin Henderson actor Gaten Matarazzo, Caleb McLaughlin, who plays Lucas Sinclair, and Byers actor Noah Schnapp on the stage in front of 6,500 fans.
Schnapp gave a little insight into his character’s role in the new season, after he spent much of the first in the Upside Down.
“Will definitely shows more bravery and then you will definitely learn how the Upside Down affected Will,” he said.
“There’s not much I can say, I don’t want to spoil anything.”
Hopper, played by David Harbour, previously went from a lacklustre cop to a key player in the fight against the evil Demogorgon.
In season two, he will face another battle but this time with himself, Harbour said.
“There’s a psychology of a heroic action where someone does something heroic and then whether or not they can live up to that or whether or not. There are perils of your own being-a-saviour complex,” he said.
Barbara Holland actress Shannon Purser made a surprise appearance but the cast told her she would not be returning for a second season.
“But there will be justice for Barb. Barb will be avenged,” it was vowed.