Erika Hernadez is a girl in Greg's grade, who only appeared in The Third Wheel. She dumped her boyfriend, Jamar Law after Jamar got his head stuck in a chair and was infamous for it, after the picture got posted in the yearbook. Greg thought of going to the Valentine's Day Dance with her, but he then thought the Jamar thing would keep staying in his head when he dates her.
- Her whole personality is not hinted in the book, but according to Greg, she is very "nice and all".
- Diary of a Wimpy Kid: The Third Wheel (First and only appearance)