Frankie Foster is Madame Foster's granddaughter, addressed as "Miss Frances" by Mr. Herriman. She is the caregiver at Foster's and helps keep everything in order. In spite of Mr. Herriman's fussiness and fixations with rules and cleanliness, having to take care of everyone and everything in the house, and Bloo's mischief-making (all of which cause her tremendous stress), she is usually very friendly and easy-going. She may seem so ewhat like a surrogate mother to Goo and Terrence and Mac's enemy and is more accurately described as a big sister to the imaginary friends. She is voiced by Grey Delisle.

Species: Anthropomorphic Human Age: 22 Hair Color: Red Eye Color: Green Clothing: Green Hoodie Jacket, White T-shirt with outlines of the Powerpuff Girls, Purple Skirt, Orange/Yellow Socks, Blue Sneakers, Earrings Occupation: Big sister of imaginary friends, Mac's enemy Allies: Bloo, Coco, Wilt, Eduardo, Duchess Enemies: Terrence, Mac Foster, Bloo (occasionally) Likes : Good behavior, Bloo respecting her, Macin jail, Mac doing mean things to her, being with everyone at Foster's, crying when Mac's not at Foster's anymore Dislikes: bad behavior, Bloo's disrespectful behavior, Mac kissing her, Mac helping her, Mac doing nice things for her Fate: spanks Mac and sends him to jail, decide to go their spears the ways, never to see each other again for the rest of their lives