Francis "Frankie" Foster (voiced by Grey Delisle) is the caretaker at her grandmother's home for imaginary friends.
Frankie Foster is the pretty, capable, easygoing granddaughter of Madame Foster. According to her driver's license, she is 5'8" ft tall, weighs 127 pounds, has green eyes, and was born on July 25, 1984. ("Bus the Two of Us" - picture shown below Infobox) However, in "The Trouble with Scribbles" episode, Mr. Herriman says that Frankie freed the Scribbles in the summer of 1988 and it flashes back to the day, in which she says, "Sorry, Mr. Herriman". In this flashback, since she is able to talk and appears to be older than a newborn, this episode suggests she is born earlier.
Frankie has apparently lived at Foster's nearly her entire life, having moved there in her early childhood. It is unclear what happened to her parents (even though never confirmed, they may have died); she seems to have lived a good life with her eccentric but lovable Grandmother.
As she grew into her teenage years, Frankie, who had spent her life in the company of Imaginary Friends, soon took on the role of taking care of pretty much everything at Foster's. She was placed in charge of cooking, cleaning the house, doing the laundry, running fund raisers, occasionally working as a handyman, driving the house residents around in the multicolored bus, and otherwise taking care of her grandmother's foster friends in most ways. Mac once referred to her as "the estate manager." Despite the fact that Frankie basically runs the house, she is still required to answer to Mr. Herriman.
She occasionally shows signs of stress as a result of her many duties, though its primary source seems to be Herriman's constant over-enforcing of the house rules and that he forever expects her to work harder despite her already full workload.
She also knows about Mr. Herriman's fear of dogs as shown in "Who Let The Dogs In?" when a couple with a lost stray dog comes in and Mr. Herriman is sent into a panic, But Frankie saves him by throwing the couple and the dog out and Mr. Herriman is still traumatized and nervous as he knows "Dogs eat rabbits".
Still, despite all her work, she does manage to keep a social life and is even allowed to go on the occasional date (assuming Mr. Herriman doesn't keep her working late with more chores). She is also often swayed by Bloo's "get rich quick schemes" and has proven to be an efficient ally in promoting Bloo's agendas when she feels she can get a good profit or an outcome out of it.
She is a fan of punk rock, as discovered in "Everyone Knows It's Bendy" and "Imposter's Home For Um… Make 'Em Up Pals". She is also proficient in web-design, creating and maintaining the Foster's web-page (as seen in "World Wide Wabbit").
According to concept art, Frankie was intended to be much younger, a teenager, and much more into punk rock than she already has been shown to be. Many drawings depicted her being always angry. While her looks have changed, she always had the same shirt (depicting a stylized version of The Powerpuff Girls, another Craig McCracken creation), green zip-up hooded sweatshirt jacket, and ponytail.
Although she is generally an in-charge, no-nonsense sort of girl, Frankie can be quite charming, as seen in "Frankie, My Dear", where Mac, Bloo, an imaginary Prince Charming (who later appeared in "The Big Cheese"), and a pizza delivery boy named Chris all develop a crush on her, and in "Good Wilt Hunting", where two nerds (Douglas and Adam) consider her to be a vision of beauty. Frankie can be skeptical at times, as seen in "Imposter's Home For Um...Make 'Em Up Pals", where she thinks Goofball John McGee isn't an imaginary friend because of his overly-human appearance. She also has an unhealthy addiction to Madame Foster's home-baked cookies, occasionally indulging in a feeding frenzy, first buying $1200 worth, and then $2400 (20 and 40 dozen respectively).
In addition, she may have a case of road rage, especially seen in "Good Wilt Hunting", where officer Nina Valarosa, Eduardo's creator, hands out tickets for various traffic violations. She also won the election for president of the house in "Setting A President", but resigned when she found out the pay was worse than her old job (and because Mr. Herriman was so sad without his old job).
Frankie also gets extremely stressed out in "Cheese A Go-Go". She has to deal with picking up Imaginary Friends, run errands and a lawsuit between her grandmother and Jackie Khones over a tuna sandwich. She also has problems with Cheese and the others throughout, which becomes worse when Bloo uses an observatory public address system to tell everyone (including her) that Cheese is an outer-space alien and in essence invites the creatures from other worlds to pick him up. The stressing out was also a central point on the three-episode movie Destination Imagination, where she escaped to a world to be pampered by a character named World, a face that could move around onto anything.
Frankie's character design appears to be loosely based on that of Lauren Faust, the show's supervising producer (and real-life spouse of series creator Craig McCracken). Oddly enough, Frankie, unlike her grandmother, seems to have never created an imaginary friend of her own; most likely this is because she grew up surrounded by them. However, she may have adopted World.
Her favorite TV show is "The Loved and the Loveless" which is a soap opera.
- Frankie will meet Jeffrey, Jaden, Sonic, Hiccup and their friends in Jeffrey, Jaden & Friends' Storm Adventures of Foster's Home for Imaginary Friends: Destination Imagination.