Who is the main character of the novel Diary of a Wimpy Kid?

Diary of a Wimpy Kid is the fictional
diary (or journal) of a middle-school child dealing with the various ins and outs of
life. The protagonist is Greg Heffley, the middle child in a three-child family; his
older brother teases him, and his younger brother uses his age (directly or indirectly)
to get away with things for which Greg is blamed. Greg is a flawed protagonist, being
selfish and self-absorbed, and is not an altruistic person. He spends the first book
trying to become more popular, and faces the typical problems of his age; he is picked
on by teenagers and he becomes jealous when his best friend becomes more popular.
Throughout the book, Greg slowly grows as a character, although he doesn't tend to learn
the correct lessons from his mistakes.