<P> Grandpa Clyde Flynn and Grandma Betty Jo Flynn (voiced by Barry Bostwick and Caroline Rhea respectively) are Linda's parents, Phineas and Candace's maternal grandparents, Lawrence's - in - laws, and Ferb's step - grandparents . Every summer, they invite the family along with many neighborhood kids to a lakehouse which Phineas calls, "Camp P&F". Though they are old, they often participate in the kids' capers . Grandpa Clyde, like Phineas and Ferb, has a great sense of mechanics, as seen in "Crack That Whip!" Betty Jo is also shown in the same episode to have a fierce rivalry with Edna Hildagard, Jeremy and Suzy's grandmother . </P> <P> Grandma Winifred Fletcher and Grandpa Reginald Fletcher (voiced by Malcolm McDowell and Jane Carr) are Lawrence's parents, Ferb's paternal grandparents, Phineas and Candace's step grandparents, and Linda Flynn Fletcher's in laws who reside in the United Kingdom . Reginald used to be a daredevil known as the Flying Fishmonger the anthem . </P> <P> Roger Doofenshmirtz (voiced by John O'Hurley) is mayor of Danville and Dr. Heinz Doofenshmirtz's younger brother . Heinz often states angrily that Roger is their mother's favorite son . In "Tree to Get Ready" Roger states that he is, "the most handsome and charming man in the Tri-State area ." </P> <P> Irving Du Bois (voiced by Jack McBrayer) is Phineas' and Ferb's self - proclaimed biggest fan . He always carries a scrapbook that he filled with images and souvenirs from Phineas and Ferb's big ideas as well as a strand of Ferb's hair . Irving has an older brother Albert, who is self - nicknamed' The Truth Detector .' </P>

Who plays the voices of phineas and ferb