Suicide Squad probably needs no introduction. Its assembled rogues' gallery of villains turned amoral antiheroes, though, needed a leader — someone to recruit them, control them, and potentially reward them. It ostensibly left the film with a problem. Who was going to seem strong enough to hold the leash on characters like Harley Quinn, Deadshot, Killer Croc, and Captain Boomerang? Who could play Amanda Waller? Answer — Viola Davis.
No one's better than Davis at projecting steely authority, and Waller's unflinching use of her power was one of the things that attracted Davis to the role. She told Empire, "When you look at her, there's nothing that seems dangerous. Her only power is her intelligence and her complete lack of guilt." In other words, that's the perfect candidate for wrangling a bunch of superpowered assets.
Critics concurred, too. Davis fulfilled the role perfectly, showing viewers everything she herself had found in her character. IGN's Joshua Yehl said, "Viola Davis completely owns the role of Waller. ... She dominates everyone she shares a scene with and makes them look ten times as small." Yehl even noted that when Davis disappears from the story, things start going downhill. Similarly, Uproxx's Steven Hyden called her "the best part of the movie by a mile."