Greg Junior (called Greg Jr) is an imaginary child who Greg Heffley thinks of as his future son and an unknown woman (believed to be Holly Hills because of her looks) in Diary of a Wimpy Kid: Hard Luck. Greg imagines asking him if he'd like to pass a hot dog to Rowley, thinking he would be the one everyone felt sorry for, although it was actually the other way around.
He looks just like a smaller version of Greg Heffley.
- Diary of a Wimpy Kid: Hard Luck (First appearance)
- Many other imaginary children of Greg are seen in the books, this is the only one with a said name.