Charlotte "Charlie" Duncan is the fourth child of Bob and Amy Duncan. She was originally the baby of the family, until it was announced in Good Luck Charlie, It's Christmas! that Amy was pregnant with Toby. She was born three weeks before her due date. Teddy, her older sister, is making a video diary for her to help her with their "special" family and some advice. She is currently 4-years-old and in preschool. She spoke for the first time in "Sleepless in Denver", but it seemed to have gone unnoticed by the family at that time.
Charlie is very cute, playful and mischievous like Gabe. She is known as a combination of all the Duncan kids as having the sweetness of PJ, the intelligence of Teddy, and the mischievousness of Gabe.
Charlie was the fourth child born to Bob and Amy Duncan. She is the youngest girl in the family. She was the baby in the family until Amy announced she was pregnant with Toby ("Good Luck Charlie, It's Christmas!").
Charlie's favorite show is The Gurgles. In fact, Teddy bought her tickets to The Gurgles Live just to get turned down. She also at one point had to watch it go to the bathroom ("Charlie Is 2!", "Let's Potty").
Gabe and Charlie have an interesting relationship. He thinks she takes away the focus from him. She seems okay with him, but she gets mad at him occasionally.
PJ sometimes uses Charlie to get girls. The affection he has for her is obvious, as his reaction toward her secret play date with a girl he was interested in was, "Aww, I can't stay mad at you." She replied, "I wuv PJ."
It is obvious that Teddy loves Charlie. She makes video diaries for her to survive the Duncan family when she's not around in every episode.
Toby is Charlie's unexpected younger brother. It was revealed that Amy was pregnant with him and that Charlie would have a younger brother or sister in "Good Luck Charlie, It's Christmas!" the latest Christmas/holiday movie. It is inferred that she may have a sense of jealousy towards the new baby, due to her no longer being the baby in the Duncan family.
This was unjust, despite the fact that he was born on her third birthday, she said that she liked him as "her present."