School is out for summer and step brothers Phineas and Ferb decide to make each day an adventure. Their bold escapades always end up cramping the style of their teenaged sister, Candace, who makes every attempt to expose mum to what is really going on, but somehow always seems to fail.

PHINEAS FLYNN
Phineas is a precocious nine year old boy with a bundle of energy. Smarter than most of the kids around him, as well as some of the adults. Phineas is constantly trying to get rid of boredom with one grandiose scheme or another.

FERB FLETCHER
Ferb, also nine, is very loyal to his step brother Phineas and will always lend him a hand or follow him on any of his harebrained schemes, no matter where they might lead. He is Phineas' right hand man, his gopher, his secretary, and his enforcer, whatever is called for by the job at hand.

CANDACE FLYNN
Phineas' older sister (15 years old) is thoroughly embarrassed by her brothers' antics but even more irritated by the fact that they always seem to get away with it. Candace has a fierce crush on Jeremy but her brothers' misadventures always seem to upset her romantic plans. Candace is a typical teenage girl. She wants to be famous, loves shopping at the mall, pop stars, the telephone and her friends. She's a fairly popular girl at school and when she's not trying to bring her brothers down, she is usually socialising or practicing her music.

PERRY THE PLAYTPUS/AGENT P
Perry seems to be a nice enough pet; he doesn't seem to do much. Whenever the boys try to train him he just gives them a blank stare and a weird chirping noise. Now and then the boys will wonder: 'Where is Perry anyway?' It's a little more complicated than it sounds. You see, the mild-mannered-brainless-pet thing is simply an act. When the boys aren't looking, Perry pops onto his back feet, checks in with his superior via videophone and is off on another adventure to save the world.

DR. HEINZ DOOFENSHMIRTZ
The bane of Perry's existence. Genius bent on world domination or at least absurd mayhem. Basically an evil genius with very poor planning skills.

JEREMY
He's the cute guy who works at the Mr. Slushy Dawg. Candace thinks he's sooooo hunky! Truth be known, he thinks Candace is pretty cute but he's a bit confused by her. Jeremy actually thinks Phineas and Ferb are pretty cool kids (and man, does that irk Candace to no end).

ISABELLA GARCIA-SHAPIRO
The too-cute-for-words little girl from down the street who has a serious crush on Phineas. Isabella is always polite and well behaved to anyone she meets and as such parents and teachers just love her. She will gladly follow Phineas anywhere regardless of the risk, as long as he assures her that it is not “kinda impossible”. Sadly, Phineas remains completely oblivious to Isabella's affection.

LINDA FLYNN-FLETCHER (MUM)
Born in the heartland of America, Linda is a stay-at-home mum with a wealth of patience and a dry sense of humour. Candace's need to tell her to see whatever it is that the boys are up to amuses her with the creative claims that her daughter makes. Deep inside – however – she is proud of her daughter. Linda was also once a pop star named Lindiana who had a one-hit wonder in the 80s called 'I'm Lindiana and I Wanna Have Fun.'

LAWRENCE FLETCHER (DAD)
Lawrence ('Lol' to his friends and family) was born in England and now lives in the states. He has a great antiques shop in town and also spends a fair amount of time travelling around the world. Those who know him best describe him as a bit of an eccentric and a kind, loving father.