Penelope "Poppy" Puff, more commonly known as just Mrs. Puff, is one of the ten main characters in the SpongeBob SquarePants franchise. She is SpongeBob's teacher at Boating School, where she teaches students how to drive boats like underwater cars. She is a pufferfish who wears a sailor uniform. She is voiced by Mary Jo Catlett.
Teaching and driving are her passions in life, being talented at both, and having taught every student other than SpongeBob how to drive. She and SpongeBob are always on an "endless quest" to get him a driver's license, but due to his reckless boating skills, they never succeed. Mrs. Puff's school is attached to a submerged lighthouse and surrounded by a stunt-driving course.
Stephen Hillenburg called Mrs. Puff the "most important" character to the show's history, saying that she "saved" the show from not being greenlit. He created her as a new main character in 1997, shortly after he pitched SpongeBob to Nickelodeon. The network gave him an order that they wanted: they would only produce the show if SpongeBob was a kid who went to school. Hillenburg was ready to decide against working with Nickelodeon because writing SpongeBob as a school-age child went against his creative vision. However, he came up with Mrs. Puff and her Boating School as a compromise, allowing SpongeBob to attend school as an adult. Because Hillenburg began his career as a marine science teacher, Mrs. Puff was a personal character to him, and he channeled many of his experiences as a teacher into her character.