|Full Name||Joshua Davidson|
|AKA||Dr. Motorcycle Boy (nickname by Rick)|
|Significant Other/s||Kate Beckett (ex-girlfriend)|
|Appearances||Josh Davidson - List of Appearances|
|Portrayed by||Victor Webster|
He first appears in "Punked" when he drops by the precinct. Unlike with her last boyfriend, detective Tom Demming, this relationship takes not only Castle, but all of Beckett's colleagues at the precinct by surprise, since she never mentioned having a boyfriend prior to Josh's showing up at the precinct.
In Knockdown, episode 3.13, Beckett tells Castle Josh is in Africa "saving the world" and that he does not know about her homemade murder board of her mother's murder that she keeps hidden in her apartment.
Beckett and Josh seemed on the verge of breaking up in Setup, the first part of a two-part storyline, when Castle enters the precinct one morning and finds them arguing at Beckett's desk. Later, Castle asks Beckett about him, and she says when he saw them earlier, Josh was leaving to go to Haiti on another Doctors Without Borders mission. She confesses to Castle that she is frustrated by his frequent absences, although his dedication to helping the less fortunate was what initially attracted her to him, and she pursued the relationship because it allowed her "to keep one foot out the door." Finally, she admits that what she really wants is a relationship where both involved can simply be there for each other and can "dive into it together." In the conclusion of the two-parter, Countdown, Josh is part of the team that rescues Castle and Beckett from freezing to death in an industrial sized freezer, and tells Castle he changed his mind about going to Haiti. For this act, Beckett forgives him and believes "we have a chance."
During Rise, after Beckett was shot, he was one of the doctors who participated in her surgery. Believing Castle was responsible for Beckett getting shot, he starts a fight with Castle, only to have Jim Beckett break up the fight. After Beckett survives the surgery, Castle sees Josh and realizes the seriousness of Beckett's relationship with Josh and doesn't want to get in the way. However it is revealed by Beckett to Castle later in the episode that she broke up with him because Josh simply wasn't enough for her.