Obviously, the return of the previous cast members, Dan Akroyd (Ray Stantz), Bill Murray (Pete Venkman), Ernie Hudson (Winston Zeddemore), Harold Ramis (Egon Spengler), Sigourney Weaver (Dana Barret), Rick Moranis (Louis Tully) and let's not forget about Slimmer!
And now onto the new team of Ghostbusters and other possibly cast members!
Ed Helms as the newer verison of Egon (the brains of the new team)
Seth Rogen as the Pete Venkman type character
Paul Rudd as the Ray Stantz type character
Anna Faris as a new female Ghostbuster
Idris Elba as the new Winston type character
Jenna Fischer as the new teams secretary
Either Kiren Culkin or Michael Cera as Oscar (Dana's child from "Ghostbusters II")
Jon Hamm as the Peck type character (the dick-head of the film who tries to stop the Ghostbusters)
Sharlto Copley as some demon leader
And
Kevin Smith as Mayor Lenny Jr (cameo role)