Supermarioglitchy4 (or SMG4 for short) is a Super Mario 64 Video Maker(not a machinimist, he says so in his channel). He makes Super Mario 64 bloopers which often have an adult theme or jokes that might seem cruel, but these jokes are intended to be humourous and shouldn't be taken seriously. He left soon after his arrival in YTR and wants nothing to do with Jacob, thus causing him to be extracted from SMG4's videos.
Supermarioglitchy4 appeared in Starman3's bloopers a few times. He appears in other people's bloopers, but most of them are fanboys/fans.
He made his first main appearance in Back to the Fourth Dimension, where he appeared in the beginning. Afterwards, Quario appeared and SMG4 declined his offer to join him as a hero.
He later chose to come with the YTR trying to get into the Fourth Dimension to follow them after Toad reminded him they left when he wanted Mario to shoot a blooper with.