Shonda Rhimes is killing on ABC Thursday nights this fall. First she granted us her smash series, “Grey’s Anatomy.” Then, she took over by premiering everyone’s favorite gladiators on “Scandal.” Now, with her new drama, “How to Get Away With Murder,” Rhimes still seems to know exactly what the people want while giving more African-American actors more opportunities on the small screen. She’s relentless about giving us all the sexy, thrill-filled drama she can pack into one weeknight, leaving us thirsting for the next seven days to fly by. As one of the most influential black women in Hollywood right now, we already know that Ms. Rhimes has plenty more up her sleeve and “How to Get Away With Murder” is only the latest. Here are some of the main characters to look for as ABC Thursdays prepares for takeoff.