Holly Hills

Holly Hills is Heather Hills's little sister, and according to Greg, one of the most popular girls in his year.

The Last Straw
She has made an appearance in the original and The Last Straw, and is briefly mentioned in the credits to one of Greg's many comics in Rodrick Rules. She was once Greg Heffley's crush, and he tried to do everything to make her notice him, until it failed when she mistakenly called him Fregley, which Greg took as an insult. Later, while signing the yearbooks, she writes a note to Greg saying that "He's Ok".

She likes Rowley Jefferson, because she thinks that he is "cute" and prefers his silliness over Greg's flirting. This is true since she wrote a note in Rowley's yearbook saying that he's funny and cute. Greg, however, attempts to break this by writing a note to Holly, but what it has caused to her remains unknown so far.

Dog Days
She does not make an appearance in this book, but is mentioned by Greg when he sees her sister Heater Hills. It appears that they both don't have the same mutral feelings for Greg like he does.

Trivia

 * In the online version, she is called "Piper Matthews" and is in a relationship, whereas in the the books, this isn't shown.