GREG
Gregory "Greg" Heffley is the main character of the Diary of a Wimpy Kid book series. He is an outcast who has, according to him, unreliable friends. He is very concerned about his popularity level and how he looks in public. He absolutely loves video games and slacking off, taking after his older brother Rodrick Heffley. As much as he dislikes his older brother, he takes up a lot of traits from him.
rowley
Rowley Jefferson is Greg Heffley's best friend in the Diary of a Wimpy Kid books. He has overprotective parents who aren't fond of Greg's behavior, thinking that he is a bad influence. Despite being the main character's best friend, as he often does idiotic things to get Greg in trouble while he gets off easily. Despite this idiotic behavior, though, Rowley always wishes the best for everyone.
rodrick
Rodrick Heffley is Greg and Manny's older brother, a bully throughout the book. He's in Junior in High School. Like Greg, he is only good at a few things, mainly music, he spends most of his time practicing, which distracts him from doing his schoolwork. It is known that Greg thinks Rodrick is lazy and stupid, though there are clues that show otherwise.
manny
Emmanuel "Manny" Heffley is Greg Heffley and Rodrick Heffley 's younger brother. He refers to Greg "Bubby", because he couldn't pronounce the word brother. Manny Heffley is thought by Greg to be evil. Greg believes that his parents treat Manny like a prince. He always gets out of trouble and gets whatever he wants by showing cute or troubled looks or crying. His parents seem to spoil him, which always makes Greg unhappy because he, nor his brother Rodrick, has ever gotten as many privileges as Manny.
Dad
Franklin "Frank" Heffley is a major character in the Diary of a Wimpy Kid Series. He is Greg's, Rodrick's, and Manny's unpredictable and serious father. He has to do all Rodrick's school papers for him because Rodrick pretends he does not know how to type. Frank is argumentative, over-reactive, strict, insecure, easily-bothered, ill-tempered, shallow, and emotional. He is constantly bothered and troubled by such small matters, such as Rodrick's typing skills and Greg's silly mistakes.
mum
Susan Heffley, more commonly called, "Mom", is the only female of the Heffley family. She's married to Frank Heffley, and is the mother of Rodrick, Greg, and Manny Heffley. She is a rather loving and caring mother, but she constantly embarrasses Greg and Rodrick, and appears to never care.