In To Kill a Mockingbird is Atticus considered to have good self-control?

Yes. Atticus is the novel's morally upright character, and there are numerous scenes that depict Atticus displaying self-control. In Chapter 11, Scout recounts how her father reacts to Mrs. Henry Lafayette Dubose's ignorant comments. Scout mentions that every time Atticus would pass her house he would politely say, "Good evening, Mrs. Dubose! You look like a picture this evening," and would wish her a happy day. (Lee 134) Atticus is aware that she makes derogatory comments directed towards him and the children. He tells Jem that it's his job to not let her make him mad. Atticus displays tolerance and self-control by not reacting aggressively or taking offense to her comments. Instead, Atticus keeps a "level head" and treats her with respect and kindness.

Later on in the novel, Bob Ewell runs into Atticus at the post office following the trial. Bob Ewell is bitter and begins to curse and insult Atticus in public. When Bob Ewell spits in Atticus' face, Atticus calmly takes out his handkerchief and wipes it off. Bob even challenges him by saying, "Too proud to fight, you nigger-lovin' bastard?" and Atticus simply says, "No, too old" and walks away. (Lee 290) This is the clearest example of Atticus displaying self-control in the novel. He understands Bob's difficult position and lets him vent his anger. Instead of reacting with anger, Atticus endures Bob's insults and calmly walks away.