The Fireside Girls are the supporting characters of Phineas and Ferb. They are a girls organization, similar to Camp Fire USA and the Girl Scouts. The only known troop in Danville is Troop 46231. This troop appears to be led (at least partially) by Isabella Garcia-Shapiro, while the organization appears to be led (and founded) by Eliza M. Feyersied. Its founding time is unknown, but it can be assumed it is relatively recent due to Eliza still being alive. It is unknown if there are additional troops in Danville, or elsewhere.
The girls show a large variety of skills, and often use these to help Phineas and Ferb with their Big Ideas. They also use their handbook, which contains information on a large variety of subjects - such as time travel and car engines "It's About Time!", "The Fast and the Phineas". Most of the activities or information listed within the guidebook are often linked to patches, and most of these patches allow them to help Phineas and Ferb in one of their many projects.
- Gretchen wears glasses and has short auburn hair. She is second in command in the troop and the first (besides Isabella) who had been addressed by name.
- Milly is the second member of the troop to be addressed by name, and the first to have been given a last name as well.
- Ginger Hirano is the younger sister of Candace's best friend Stacy. She has a crush on Baljeet.