iMustDestroyAll (referred to as MustDestroyAll) was a main antagonist in the AngryGrandpa series - he was the centre of a series of pranks on the titular Angry Grandpa and has since became a legendary figure in the context of the show, to the point he now shares the position of Angry Grandpa's nemesis alongside "The Hag".

The basic contect of iMustDestroyAll is that he is a psychotic youtube personality that stalks AGP and threatens his life, with Michael (often known as "Pickle Boy") showing Angry Grandpa youtube videos designed to show iMustDestroyAll entering Angry Grandpa's home. He claims to be a demon from Hell, wears black clothing with a demonic mask, and uses voice-distortion technology to give him a deep and demonic voice. When Angry Grandpa found out that Michael was behind the iMustDestroyAll pranks, he destroys his Xbox 360.

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