From the Super Mario Wiki
Tolstar, the king of Stardust Fields, is a greedy trickster found in the game Mario & Luigi: Superstar Saga. His name probably derives from Tolstar forcing people (such as Mario and Luigi) to pay a toll to get across the border in Stardust Fields (he also has star patterns on his forehead and stomach). It could also be either a play on the Russian word толстый (tólstyj), meaning "fat", or a portmanteau of the Russian author Tolstoy and the word star.
When Bowser is stuck in a cannon in Stardust Fields, Tolstar charges the brothers all their Coins to get Bowser out the cannon and keep the incident a secret. Mario offers the coins, but they are all Mushroom Kingdom coins, and they are worth much less in the Beanbean Kingdom. Tolstar demands 100 Beanbean Coins, and the brothers must search Stardust Fields for them. Upon collecting them, however, Tolstar still refuses to set Bowser free and attacks Mario and Luigi. He is the first major boss in the game.
In battle, he attacks by throwing spiked balls at Mario or Luigi, and he even gives a hint by saying that remembering which hand he throws it. In battle, Tolstar sometimes laughs before tossing a spiked ball; this means that the ball bounces over the brother if the brother does not jump.
After defeating him, the Bros. are about to free Bowser, but Sergeant Starshade, annoyed with the Koopa King's complaints, shoots him out of the cannon (causing him to crash through the unconscious Tolstar) into parts unknown. The brothers advance to Hoohoo Village, where they are accused of kidnapping Prince Peasley by the Beanbean Guards. However, a beat-up Tolstar flies over (using the miniature wings on his shoulders) to inform the guards that the two are Mario and Luigi, that they are tough, and that they did not kidnap the Prince. He is never seen again after that.
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