He was once the sidekick of Krusty the Clown, but he framed him for armed robbery in 1990 so he could run the show. Bart Simpson however exploited his scheme and ever since he has been trying to kill Bart, or do something directed to him. After being foiled the 11th time, He lost hope as a criminal mastermind but it was restored when Slade bailed him out and made the mastermind a deal he couldn't refuse.Sideshow Bob eventually went on to become one of Slade's main staff alongside Anti Cosmo, Eddy, Celes, Hades, Mojo Jojo and HIM. He is still one of the newest members, and while Hades is a main provider of Slade's armies, SIdeshow Bob's notrorious as a criminal mastermind has opened up connections for Slade to gather more folowers.
His theme is a parody of the Cape Fear theme in Martin Scorese's Cape Fear of 1991 and in said episode he parodies a great deal of the antagonist Max Cady.Sideshow Bob was Slade's best man at his wedding as Anti Cosmo gave him permission as he was the one planning everything
Sideshow Bob was in Slade's Castle as he greeted Slade's returned and wondered why Bender and Hiccup were there, He backed off when he learned they were all working together. Sideshow Bob when questioned about the biometals, he recalls how he met the creator Ciel which Bender and Skipper catch on with. Alongside Slade's other members Sideshow Bob finds the destroyer and they all destroy it
Sideshow Bob with other members of Slade`s Ensemble find Black Star and make an allegiance with him
His evil laugh is The4everreival's favorite evil laugh in all animation.
While Sideshow Bob was a member of Slade's team since Slade Strikes Back, He once again joins up with Slade after Blackpool to defeat Eobard Thawne. Put in charge of the musicial entertainment Bob relishes in this though it's short lived when he and Mojo both get Phineas and Isabella's letter, find Curveo attacked by THe Joker and ultmatiely invaded by Thawne. He does research on the invasion while the others attack Thawne's crew. Sideshow Bob manages to identify that Toffee is who did this.He along with the other members of Slade's meeting to discuss their attack that Thawne commited on them and his theft of a precious item that Slade and Anti Cosmo claimed in a past adventure.
Sideshow Bob Travels with Slade and his team to 2010 to track Thawne and recruit Eddy and The V Team to help them as well as Slade's past self. Sideshow Bob is also one of the associates who works with Harry and Celes to figure the husks they found upon inspection while Slade is away. He also participates in The Ensemble battle with Deathstroke and his associates who invaded the ship and helps Celes and Mojo Jojo deal with Malcolm Merlyn and Welton.