|Full Name||Johnathon James Castle|
|AKA||John or Johnny|
|Parents||Richard Castle (father)
Kate Beckett (mother)
|Siblings||Alexis Castle (daughter)|
|Portrayed by||Morgan Gingeriech|
Johnathon "John" James Castle is the younger twin son of Richard Castle and Kate Beckett. He has an older twin brother Richard Castle Jr, by 3 minutes, and two older half-sisters, through his father, Alexis and Lizzie. John calls his brother Richie, because he can't pronounce Richard or he often calls him Ruch.