Mushroom Retainer
Mushroom Retainers are advisers to the leader of the Mushroom Kingdom. The most famous Mushroom Retainer is Toad. Mushroom Retainers assist Princess Peach in her administrative duties of the country. They first appeared in Super Mario Bros., where they were kidnapped along with the Princess by the evil King Bowser. One Mushroom Retainer appeared at the end of each castle and thanked Mario or Luigi for rescuing him. However, each one infamously stated that the princess was in another castle.
Mushroom Retainers also appear in Super Mario RPG: Legend of the Seven Stars. In this game, there are six retainers (with Toad being one of them). These Mushroom Retainers serve the Chancellor of the Mushroom Kingdom, as he is in charge of the kingdom until Peach returns.
Trivia
If someone looks closly at the mushroom retainers in Super Mario Bros. 1, it lookes like he is giving a vulgar gesture to the player. It is not known if this was intentional, or a glitch in the programming