The Muddy Hand

 The Muddy Hand is the main antagonist in the fictional story of the same name as well as the horror movie "Hello: You're Dea dand a fictional villain from the Diary Of A Wimpy Kid: Dog Days book and film.

Book
In the book the hand appeared as the main villain in the horror movie Greg and Rowley were watching of the same name. According to Greg the movie was very cheesy and campy however he became terrified at the end when the film's twist appeared (being that whoever sees the hand next would be its newest victim and the Hand turned to the camera at the end of the movie). Greg appears paranoid about the hand catching him throughout the remainder of the novel however after Dog Days the hand is never mentioned again meaning Greg probably got over it.

Movie
In the movie the hand had even less of a role and only appeared as a campfire tale told by Fregely during the Wilderness Explorer camp. Greg while being afraid of the story didn't believe it however when he saw his camp manager pretending to be the hand he jumped and screamed in fear and later after seeing his dad's muddy hand emerging into the tent he whacked him with a mallet in fear and defence. The hand has never been mentioned again since.

Trivia

 * In the movie version of Rodrick Rules, Greg and Rowley watch a horror movie called "The Foot" which is an obvious reference to the muddy hand.