|Name||Aunt Cakey (Nickname, real name unknown)|
- "Somebody take this kid to a speech therapist!"
- -Aunt Cakey in the online version
She appears in Diary of a Wimpy Kid Online, on November 14 and 25 as cameos, and from then on, has only been mentioned by Greg. She later appears in Diary of a Wimpy Kid: Hard Luck as Susan's eldest sister.
She appears to hate kids and whenever Rodrick or Greg would get bored, she would make them do household work. According to Hard Luck, she had never married anyone and she is Susan Heffley's oldest sister. She had a dog named Rudy in the online version. In Hard Luck, the last time she babysat Greg, she made him sit down on the couch for a long time and then made him take a nap, although Greg doesn't do that anymore, even then. However, when she tells him to not touch the iron, Greg did so. Greg ended up getting a second-degree burn from the clothes iron. Ever since, Susan has never let Aunt Cakey babysit Greg again.
She has an earring, she wears a dress, and she has a bun. It is unknown what color her clothing is due to the book's black and white nature. In the book, she has a rounder face and wears slippers or sandals. She also has no wrinkles.
- She is the only woman that doesn't like Manny.
- Aunt Cakey seemed to be on edge when she was babysitting Greg. It could be possible that she had babysat Rodrick once, which, knowing Rodrick, explains her reason for being on edge.
- Aunt Cakey believes Manny needs a speech therapist as he has problems with his "R"s and "L"s.