4. Grant Gustin as Larry Underwood
Grant Gustin has a knack for playing urgency and desperation. Currently dominating the ratings on the CW's "The Flash" as the titular hero, he is usually tasked with quickly and efficiently portraying Barry Allen's conflict of loyalty among his multiple father figures, his duplicity of being a kind and attentive friend while also flaking on everyone to save the city/timeline/dimension. He's also got a terrific singing voice and a small-town likeability.
Enter the rock star, Larry Underwood. As the performer and writer of a new hit song, Larry is every bit the charming lothario celebrity on the surface in order to properly hide the narcissistic drug addict and irresponsible man-child underneath. And then the apocalypse draws him into a surrogate family, then a community, and then a life-defining mission. Gustin would not only be able to perform Larry's musical talents but also his transformation into a responsible man with a complex belief structure. It's a coming of age story fit for the "Glee" alum.