Madison Miller, sometimes Maddie, is the daughter of Jeannie and Kaleb Miller, and the niece of Dr. Rodney McKay. She often enjoys making and baking chocolate chip cookies with her parents and has a sweet tooth for them too. She also enjoys playing with her mother and can do ballet. She was Jeannie's first and, so far, only child.
In 2006, she was playing with trains, and was pushing a toy train over a toy bridge, when her mother had a revelation on a theory of bridging two separate realities. When Dr. Rodney McKay visited the Miller household, Madison greeted her uncle by asking if he brought her anything. (SGA: "McKay and Mrs. Miller")
One year later, she was oblivious to what happened to her mother, since she didn't know she was kidnapped. Both Kaleb and McKay made up a story that she was away for a while. (SGA: "Miller's Crossing")
- In an alternate reality, she had two younger brothers named Bradley and Robbie. Her godfather was her uncle Rod McKay. (SGA: "McKay and Mrs. Miller")