Jeffy François, or simply referred to as Jeffy, is one of the three main protagonists (alongside Mario and Bowser Junior) in the SuperMarioLogan series. He is the adoptive son of Mario and Rosalina. The character was created by Logan Thirtyacre and Elaina Keyes.
He is the oldest child of Nancy and Jacques Pierre François, and the older brother of Feebee, but since Feebee and Jacques died and Nancy went to jail in Jeffy’s Parents!, he is now the adoptive son of Mario and his wife, Rosalina.
He is the secondary antagonist in Season 8, and the main antagonist in many episodes including Jeffy’s Tantrum!, Jeffy Plays Fortnite!, Jeffy’s Punishment!, Jeffy’s Lie!, Jeffy’s Big Mess!, Hurricane Jeffy! Jeffy’s Bad Word!, and his debut episode Mario the Babysitter!. Despite being an antagonist in these episodes, he is the main protagonist in some SML episodes, such as Detective Jeffy!, Jeffy’s Parents!, Jeffy Gets Bullied!, and Jeffy’s Bad Christmas. In some episodes, he is deuteragonist and tritagonist to Mario in the Mario/Jeffy videos.
Since his debut, Jeffy has proven to be very popular, most particularly with younger children. Despite his popularity, he has also caused much trouble and controversy and is overwhelmingly unpopular with many older SML fans.