Theory: The Chancellor is the Toad Minister

Abstract
Super Mario RPG’s Chancellor is the same person as the Toad Minister from Paper Mario.

Arguments

 * Argument 1: Both characters have extremely similar designs, being moustachioed green toads with imperial handlebar moustaches. The most major difference in the two designs is with the color of the moustache, but that could easily be explained by the Chancellor ageing between Super Mario RPG: Legend of the Seven Stars and Paper Mario.


 * Argument 2: Both the Chancellor and Toad Minister stand in the exact same pose, with both arms behind their backs.


 * Argument 3: Both the Chancellor and Toad Minister had very similar roles between their respective appearances. In Super Mario RPG: Legend of the Seven Stars, the Chancellor watches Peach’s Castle while she’s kidnapped. He’s also in charge of the castle’s affairs. The Vault Guard Toad tells Mario that he’ll need permission from the Chancellor to enter the vault, for example. In Paper Mario, the Toad Minister states: “I am the Minister of Princess Peach's Castle”, “[Princess Peach’s] beautiful castle is being run by Bowser’s horrible staff of rejects.”, as well as “nothing fills me with more joy than serving this castle with my heart, and soul...” It’s also implied by Goombario that he’s the one who organises parties at the castle. Both characters also put a lot of faith in Mario, trusting him greatly and requesting for him to save the Princess.

"Oh....... I... I am delicate! I'm behaving like a delicate princess, just like the Ministers taught me to! I love to be delicate!♥"
 * Argument 4: Both the Chancellor and Toad Minister have (or at least had) very similar roles in Peach’s life and have very similar opinions in regards to how she should act. In Super Mario RPG, the Chancellor is appalled by the idea of Peach going on an adventure with Mario, due to the fact that she’s a Princess. In Paper Mario, when Twink questions whether or not Peach is as delicate as she seems, Peach states:

- Princess Peach


 * Clearly the Toad Minister taught her to be like a “delicate princess”, which would be completely in-line with the Chancellor’s actions.


 * Argument 5: Finally, both the Chancellor and Toad Minister have the very same Japanese name, that being “Mushroom Minister”.