In case Nate Parker doesn't crack the Best Actor field, they'll need at least one actor to represent the band of actors and the film itself.
Oscar Isaac, The Promise: Isaac is somebody whose profile has risen thanks to Star Wars and he'll also be seen in the upcoming X-Men: Apocalypse. One thing that helps his potential cause for The Promise is that it's a period drama by Terry George who guided Don Cheadle and Sophie Okonedo to Oscar nods for Hotel Rwanda. Also, it makes sense to honor a man whose namesake comes from the trophy, right?
Ben Mendelsohn, Una: Another actor who is seeing his profile rising thanks to the show Bloodline and the upcoming Rogue One: A Star Wars Story. While Una doesn't have a U.S. distributor yet and while the play the movie is based on is a two-hander since he'll likely share the screen with Rooney Mara, he's the kind of actor's actor that tends to be placed in they category.
Liam Neeson, Silence: On paper, I think Neeson is the winner. One reason is Scorsese, another is that Supporting Actor is often the veteran achievement award, and since the film is about a couple of priests retrieving their kidnapped mentor and Neeson is the kidnapped mentor, that could lead to some emotional clip scenes. So their might be a sense that it's Neeson's year.
Edward Norton, Collateral Beauty: With 3 nominations under his belt, Norton I think is maybe one or two nominations away from having a trophy on his mantle. Out of the actors in his ensemble, I could see him being a representation for the whole cast.
Mahershal Ali, Moonlight: He's set to have a prolific 2016. Could he benefit from the film which looks to have a lot of promise?
Tadanobu Asano/Adam Driver, Silence: Double dipping in this category, perhaps?
Aaron Eckhart, Sully: Starring in a Clint Eastwood film and he's also got the boxing drama Bleed For This to aid his cause.
John Goodman, 10 Cloverfield Lane: Pretty please?!
Steve Martin, Billy Lynn's Long Halftime Walk: They gave him an Honorary Oscar. Maybe he could finally be in the running for the real thing.
Nick Offerman, The Founder: Comedian going serious.