Gregory "Greg" Heffley is an American middle school student and the main protagonist of the Diary Of A Wimpy Kid series. He is believed to be loosely based on Jeff Kinney when he was in middle school. Greg 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. He takes up a lot of traits from Rodrick (such as selfishness, laziness, etc.). He also has an interest in cartooning and making comics. He was played by Zachary Gordon in the live-action movies Diary Of A Wimpy Kid, Diary Of A Wimpy Kid: Rodrick Rules, and Diary Of A Wimpy Kid: Dog Days, even though the books are whiteboard animated. Greg is portrayed by Jason Drucker in the live-action film, Diary Of A Wimpy Kid: The Long Haul .


Greg's first balloon appeared in 2010, to help promote the live-action Diary of a Wimpy Kid movie by 20th Century Fox, and the newest book in the series, The Ugly Truth. This balloon featured him clutching his prized diary as he strolls down the streets of New York. This balloon was retired in 2015.

In 2016, he was transformed to more closely resemble Greg’s colorful new look as illustrated in the latest Diary of A Wimpy Kid books, Greg is ready for the winter decked out in red snow boots, blue puffer coat, red ear muffs and a green/yellow striped scarf. While he may be bundled up for the Thanksgiving Day weather, the new balloon will sees Greg clumsily taking a tumble down the route with his arm outstretched to break his fall, surely having slipped on an icy surface because he had his nose buried in his “Diary”…oops, journal! This balloon still appears as of 2018.