Dixon
Dixon is the antagonist to Mildred's protagonist throughout the majority of the film as he is a racist and man of great hate. Ironically, he chooses to be on Mildred's side in searching out the man who raped and killed her daughter after he was against her for so long in the story.
Dentist
Mildred goes to the dentist, and he threatens her about taking down the billboards as he has his drill approaching her mouth. Ironically, she takes the drill from him and drills a hole in his thumbnail.
Burn it Down
Mildred decides to burn down the police station as an act of rebellion against a police force that she believes hasn't done enough to catch her daughter's killer. Ironically, Dixon is in the station and she didn't know it; he is burned badly by her act.
Father
The town priest pays a visit to Mildred in order to tell her to take down the billboards. He believes that she will listen to him because of his position in the church. Ironically, she calls him out for being culpable in the Catholic church scandal of sexual abuse against young boys, and declares that she will not take advice from a man who belongs to a "gang" that she doesn't agree with.
Kids will be kids
While Mildred is dropping Robbie off at school, a kid throws a container of liquid on Mildred's car. She gets out and wants to know who did it. The kid pretends to not know and ironically Mildred kicks him in the genitals. She is a woman willing to do things that no one would ever expect and this moment makes it clear.
