Sicario
As revenge for Alarcón having his henchmen visciously murder those Alejandro cared for, Alejandro arrives at Alarcón's estate, kills all those in his path to the dinner table of Alarcón's villa, sits down at the table with Alarcón, his wife and children, explains why he's there so everyone knows, then phhut ... phutt ... murders Alarcón's children, then phhuut ... his wife, then executes Alarcón himself.
One of the coldest scenes I've ever watched play out, even though you knew it was going to happen once Alejandro sat down.