Toadsworth (キノじい, Kinojii) is an elderly Toad who is Princess Peach's loyal servant. As such, he is very concerned about her safety and worries about her constantly. He acts as a father figure to her and is constantly seen fussing about her well being. Toadsworth also prides himself on being polite as he maintains good manners even if faced with a rude or insulting person.
As a minor character in Super Mario Sunshine, Toadsworth has little to do with the main story despite the game being his debut title. There is little opportunity to interact with him as he only has any significant dialogue during the opening cutscene and the introduction for the game that follows.
After Sunshine Mario appeared in Paper Mario: The Thousand-Year Door. He helps Mario at the beginning of the game but stays in an inn at Rogueport for the remainder of the adventure. Toadsworth doesn't have much to do with the game as he only serves to provide details about his time with Peach before she is kidnapped. Paper Mario 2 also marks his debut in the series, as he did not appear in the first game.
"An elderly, refined Toad steward of Princess Peach, with a white beard and small glasses. He advises Mario on his adventures and has appeared in many games since his debut in Super Mario Sunshine. Although he can get annoyingly flustered, it's only because he cares for Peach. In the Japanese mah-jongg game Yakuman DS, Toadsworth appears as a competitive opponent."
Young Toadsworth is Toadsworth as he was a mid-age adult. His first appearance was in Mario & Luigi: Partners in Time, where he went into the future and met his older self. In the past, the younger Toadsworth has a Black mustache, and different colored clothes. For some reason the two don't seem to get along well, but can team up to perform moves to teach Mario and Luigi. He is constantly trying to make Princess Peach happy, just like his older counterpart.