Justin Bieber (also known as Justin Beaver or more colloquially JB) is a minor character in the SMG4 series.
He is a Canadian singer, best known for his semi-infamous song Baby. He has gained many fans and haters alike over social media, and to this day is a controversial figure.
He appears in some of SuperMarioGlitchy4's bloopers. He originally auditioned for the role of Mario, as seen in SM64: Meet the Mario.. Meanwhile, his songs and pictures of him have been used as weaponry due to how atrocious everyone finds them. Nevertheless, many characters, including Toad, SuperMarioGlitchy3, Bonnie, and especially Bowser are Bieber fans.