Toadsworth is a character who was first appearance in Super Mario Sunshine. He is the steward of Princess Peach Toadstool and back when Peach was young he babysat her a lot as revealed in mariowiki:Mario and Luigi: Partners in Time.
In the Toonking2 Fan Comic series on Deviantart.com, Mario and Friends , it was revealed not only that he was Peach's Royal Steward but he was also the eldest of Peach's Siblings, like Claudia, Cosmo and Pearl. It also revealed that he also had a forever 18-year-Old Vampiric Twin Sister Samantha T. and that they both were also raised as orphans by The Mushroom King, though he doesn't get along with her very well nor does he get along with Peach's vengeful threats against Bowser kidnapping her too much (which is why he calms down Peach without consequence).
Toadswort only appears in the episode Super Chef Cook-Off, where he is one of the three judges.