Curtis Litz is a hoax made up by Greg in Double Down due to Greg needing an excuse as to why he never finishes the apples Susan Heffley gives him. When she told Greg to bring the apple core to her, to show that he finished the apple, he forgot to. He said to his mom that Curtis Litz was the one who took his apple away from him and ate it. Greg wrote a letter to Curtis that he should not take his apple again because he needed it for his nutrition. But Greg wrote a fake letter to himself from Curtis instead. To make sure his mom knew how bad the kid was, he added a rude drawing at the end of Curtis' letter. The next day, his mom took a letter, demanding to speak to Curtis. The secretary told her that there was no student named Curtis Litz. So Susan Heffley asked Greg about him and he said that he could be home-schooled. This means that he could be lying that he was the one who give his apple to Rowley Jefferson during lunch and give him the core as he was nervous. One day at church, the Heffleys sat behind the Bartleman family and they had a son, Tevin Bartleman, who perfectly fit the description of Curtis Litz, and after church, Susan Heffley got angry and told the Bartleman's that they were raising "a rotten kid" and they owed her some apples. It was actually the opposite, as Tevin was a good kid who volunteered at the soup kitchen every Saturday. Eventually, Tevin became enemies with Greg retaliated against him during school.
- Diary of a Wimpy Kid: Double Down (First and only appearance)