Created by Phineas and Ferb co-founders Dan Povenmire and Jeff "Swampy" Marsh, he first appeared in the show's pilot episode, "Rollercoaster."
[7] Candace Gertrude Flynn (voiced by Ashley Tisdale) is characterized as Phineas's fifteen-year-old biological sister and Ferb's stepsister.
Whenever she attempts to "bust" her brothers, Phineas and Ferb's work unintentionally disappears before their mother sees it, and the boys appear to be involved in simple activities.
Also, when Phineas delivers a heartfelt speech at his birthday party thanking his friends, Candace seems so touched that she destroys another disc she intended to use to bust him and Ferb ("Clipshow").
Depending on the episode, Dr. Doofenshmirtz's main goal is to either destroy or rule the tri-state area, which was suggested to him as a teenager on a failed date with Linda Flynn-Fletcher as a starting point before taking over the world.
However, a few of his schemes were quite successful, such as in the 2014 special Phineas and Ferb Save Summer, when Doofenshmirtz moved the Earth away from its original orbit to bring on an early autumn, much to Perry's distress.
[14] Throughout the series, Doofenshmirtz's flashbacks (which are often shown after Perry has been captured) explore his mentally abusive and lonely childhood growing up in the fictional village Gimmelshtump, Druelselstein.
Doofenshmirtz usually monologues[2] and displays acts of cartoon-style physical violence[15] towards his nemesis Perry, a skilled anthropomorphic platypus secret agent.
He was also not called a bully nearly as often, especially as the series went on, but Baljeet remained his primary target, the two even singing a duet in one episode where they describe each other as "frenemies" and "my least favorite brother", while his relationship with Phineas became a one-sided rivalry on his part when he was not aiding him.
Buford also began displaying hidden talents and interests, such as speaking French in "Summer Belongs to You", to give his character more depth, though he still wished to keep this information secret under threat of pain for fear it would ruin his tough guy image.
Unaware of the large-scale projects that Phineas and Ferb create on a daily basis, Candace often drags her away from other interests in an attempt to get the boys in trouble.
[26] She went on a date with Heinz Doofenshmirtz during their mid-teens, and she was the one who inspired him to take over the tri-state area as a starting point for worldwide domination when he sarcastically stated that he would rule the world.
He usually appears in a Nehru jacket on a giant screen giving Perry instructions for his next mission to stop Dr. Heinz Doofenshmirtz's endless attempts to take over the tri-state area.
(Organization Without a Cool Acronym) in charge of video taping Monogram when he is being interviewed and talking to Agent P. He is a bit careless, wears glasses, and sometimes forgets to focus the camera correctly.
[28][29] In "Phineas and Ferb's Quantum Boogaloo", it is revealed over a phone call with "future Candace" that she has become President of Uruguay, twenty years after the series takes place.
[31] Also, despite denying it so many times, Vanessa admits that she may be a little evil, as she once helped her father escape from custody by posing her hairdryer as a pistol to fool Major Monogram and Perry into releasing Doofenshmirtz, as shown in the special Phineas and Ferb: Summer Belongs to You!.
Other members of the troop: Norm (voiced by John Viener) is a giant robot man created by Dr. Doofenshmirtz to destroy Perry the Platypus.
Later in the series, he is depicted as Doofenshmirtz's sidekick and servant who makes frequent mistakes such as cooking eggs with the shells on or serving Doof chocolate cake for breakfast, though always staying cheery.
[33] Although he does not like dog food, Pinky will eat just about anything–especially his favorite; grilled cheese sandwiches (as seen in the episode "Journey to the Center of Candace") and even inedible objects, having once swallowed Isabella's Fireside Girl sash.
This enrages Doof, who is convinced to use his latest -inator, the Poop-inator, to hypnotize the tri-state area pigeons into raining feces on Roger during his speech, when he receives the Key To The City.
Django is the son of the artist Beppo Brown from "Oil on Candace," who is famous for his work in making giant creations, from refrigerators to dental floss.
Just like Major Monogram, she usually appears on a giant screen giving Pinky instructions for his next mission to stop Professor Poofenplotz's endless attempts to take over the world.
Professor Esmeralda Poofenplotz (voiced by Amanda Plummer) is an old mad scientist and the nemesis of Agent Pinky, Isabella's pet Chihuahua.
Sherman "Swampy" (voiced by Steve Zahn) ended up working at the Danville Public Library, believing he had lost his sense of rhythm.
Due to the rivalry between his father and Dr. Doofenshmirtz, he and Vanessa try to keep it secret from the two of them, aided by Perry and Carl (though the latter briefly blackmailed Monty in hopes of getting his help in earning Major Monogram's approval).
In the special Phineas and Ferb Save Summer, Monty played a major role as he attempts to help rescue all of the captured agents and defeat the villains of L.O.V.E.M.U.F.F.I.N.
Aloyse Everheart Elizabeth Otto Wolfgang Hypatia Gunther Galen Gary Cooper von Roddenstein (voiced by Joe Orrantia), or Rodney for short, is a bald evil scientist and a member of the villain organization L.O.V.E.M.U.F.F.I.N..
Rodney would later go on to appear in the 2014 episode special, "Phineas and Ferb Save Summer", where he learns that Doofenshmirtz has actually succeeded in moving the Earth away from the Sun to an early autumn with his latest -inator.
In an interview, Dan Povenmire stated that the head had originated from a storyboard panel that writer Mike Diederich had drawn which director Rob Hughes found hilarious enough to create an entire bit around.
Albert (voiced by Diedrich Bader), is Irving's brother who appeared in "Not Phineas and Ferb", "The Doof Side of the Moon", and "Nerds of a Feather".