Charlie Thomas is Kristy Thomas's oldest brother. He is sixteen at the beginning of the series and seventeen from [[Kristy's Big Day]] on. He is assumed to be a senior in high school, since occasional references are made to him going to college "next year" and he is shown considering various colleges in [[Mind Your Own Business, Kristy]]. He plays varsity football, intramural basketball, and helps Kristy coach the [[Krushers' Softball Klinic]]. He taught Kristy the basics of baseball when she was little.
He drives Kristy and later Abby to BSC meetings. In [[Mary Anne and the Great Romance]], he acquires his first car, which is soon nicknamed The [[Junk Bucket]].
He dates [[Sarah]] from the time of [[Kristy+Bart=?]] (probably earlier) until [[Mind Your Own Business, Kristy]]. In the latter book, he becomes interested in [[Angelica]], who frequently sits for the [[Hsus]].