In the online book, Rowley is said to own a PlayStation with 42 games. However, in the movie, Rowley is shown to have a Wii, meaning that he probably upgraded his console. Jeff Kinney said that he named Rowley after a city in Massachusetts because he thought it would fit the character as being "slow and innocent and pure". Aunt Cakey is Susan's oldest sister. She is single and has no pets or kids, suggesting that she doesn't like kids. When she stayed with the Heffleys when Greg was little, she kept all fragile items out of his reach and made him take a nap. When she told Greg to not touch the iron, he couldn't stop thinking about it and pressed his whole hand against the iron, giving him a second-degree burn. Susan has never trusted her with babysitting since. Janusonis, Michael. The Providence Journal, March 25, 2011, " Being 'Wimpy' pays off for Scituate's Robert Capron". Accessed March 31, 2011.

In the book series, he has 7 strands of hair that is flat on his head and is wider than Greg's. He has two large teeth and his mouth never appears to be closed, except for a few occasions. In the film series, Susan is portrayed by Rachael Harris in the first three films, Alicia Silverstone in The Long Haul, and Erica Cerra in the animated films. In the first three live-action films, he is portrayed by Andrew McNee, while Billy Lopez voices him in the 2021 animated film. Notably, the live-action films rename the character to Coach Malone while the animated film retains his original name. Albert Sandy is a minor character who often talks about rumors he has heard. The validity of his statements is unconfirmed. One of his statements which was disproved by Greg was when Albert told him that it was "medically impossible for a girl to fart". Some of Albert's statements make no sense, for example, he said a man got decapitated when he sneezed.No-one does the straight to camera narrative style of the diary better than Kinney ... This is as authentic and funny as the original Wimpy Kid books and makes just as irresistible reading.' - Andrea Reece, LoveReading4Kids Reviewer In the online book, Rowley is said to own a PlayStation with 42 games. However, in the movie, Rowley is shown to have a Wii, meaning that he possibly upgraded his console. In the film series, Rowley is portrayed by Robert Capron in the first three films, Owen Asztalos in The Long Haul, and Ethan William Childress in the animated films. Joshie is a European singer (possibly British) who is Rowley's favorite idol. Greg believes that Joshie is for six-year-old girls, but Rowley ignores him, saying that Greg is jealous because he was the one who "discovered" Joshie. However, despite Rowley's opinion, Joshie appears to be a singer that is mainly idolized by females (specifically 6-year-old girls). In The Deep End, Gary is never seen, but it is revealed that he used to own a camper, which had been parked in Gammie's driveway for two years. She gives it to Greg's family after being fed up with it taking up space in her driveway.

Gerald is Susan's cousin from California who lived with the Heffleys for a few months after Greg was born, which he embarrassingly reminds Greg of every time he sees him. In the 2017 adaptation of The Long Haul, the Heffleys gained the pig in a similar way to the 9th book. After causing havoc in a hotel room, and nearly leaping onto a busy highway, the Heffleys decide to get rid of the pig by donating it to a petting zoo, much to Manny's dismay. Later on, when Manny can speak fluent Spanish, he directs a helpful towing company to the petting zoo, reuniting him with the pig. Rowley's best friend Greg Heffley has chronicled his middle-school years in thirteen Diary of a Wimpy Kid journals. Now it's Rowley's turn to give his side of the story. But Rowley has agreed to tell Greg's story along the way, too. (After all, Greg says one day he will be rich and famous and the world will need to know how he managed it). After Greg inadvertently causes the Snella family to move away due to a foul smell which (unknown to the Snellas) was caused by Greg dumping deviled eggs into a plastic plant, he decides that he should find a way of sneaking deviled eggs into Fregley's house.Benjamin "Benjy" Heffley is Greg's cousin, whose parents are Greg's Uncle Tony and Aunt Patricia. The last time Greg saw Benjy, he could only say "No!" or "Shut up!", respectively. Now he can speak in full sentences and read chapter books but is still not potty trained and usually wears a diaper. Benjy is asked to be a reader at Uncle Gary's wedding to Sonja – a position that Greg had initially expected to fill.

Holly makes a cameo in The Ugly Truth talking to some of her friends, and this is her most recent appearance in the books, though she was shown in a chart Greg drew in The Third Wheel as one of the many girls interested in Bryce Anderson. It is never revealed what country Rowley went to on his trip to South America in the book series, but the online book states that he went to Brazil. It is said in the first film that Rowley went to Guatemala, although Guatemala is in Central America.Gammie is briefly mentioned by Greg in Cabin Fever when he says she gave a miniature carousel that held spoons from all over the world to Greg's family five or six years before.