Seeley Booth, portrayed by David Boreanaz, is a former Army sniper with the Rangers, who is currently an agent with the FBI. He frequently consults with Dr. Brennan and her team, acting as a liaison between the FBI and the Jeffersonian institute. When it comes to solving crime, Booth has a very different approach than Dr. Brennan and her team, preferring a more human, interpersonal and intuitive set of methods. While he finds the information Dr. Brennan and her team uncover invaluable, he often finds their means overly convoluted, and restrictive, and adds his intuition and knowledge of people on top of it — something that clashes with Dr. Brennan's hard, objective and analytical approach which is mindful of its own limits.

While Booth tries to keep personal and professional life strictly separate, aspects of his personal life leak through. He is a religious man by nature and a practicing Catholic, seeking through the FBI to atone for the lives he took as a sniper by placing other killers behind bars. While in the Army he was apparently tortured and also wounded trying to protect an unarmed comrade, both of which left him with physical scars. He was romantically entangled with a blonde lawyer named Tessa. He also has a four-year old son named Parker with his ex-girlfriend, Rebecca, who seems quite hostile toward Booth for unknown reasons. He has also mentioned having a brother named Jared. He used to have a gambling problem but has since quit.

Booth rekindled a relationship with Dr. Camille Saroyan when she joined the Jeffersonian team. The relationship ended after an intense case, with Booth asserting that on-the-job romantic relationships endangered the team in high-pressure situations.

While Booth and Brennan maintain a professional relationship and friendship, there is also the beginning of a romantic tension within their relationship. Particularly, Booth is shown to be jealous of Temperance's romantic relationships in "Two Bodies In The Lab" (1x15) and "The Woman In Limbo" (1x22).

Booth does not socially fit in with the collection of "geeks" (whom he and his FBI colleagues refer to as "squints") that make up Dr. Brennan's team. Booth fills out the stereotype of the "all American boy" — now all grown up — very well. He is world-wise, socially at ease with people, and apparently at ease with women (a contrast to the humorous social bumbling sometimes exhibited by some of Dr. Brennan's team).

Booth is a fan of Classic rock and Arena rock music. He has expressed great affection for the group Foreigner and poked fun at Bones for her interest in new world, jazz music. He also likes the band Poco and sang their song, Keep on Trying with Bones.

Booth is known to be fiercely protective of both Brennan and his partnership with her. He also seems to get on quite well with Angela and Hodgins, but finds Zach's cold naivety a little disconcerting, to the extent that he leads Zach to believe that the fact that Booth rarely acknowledges his existence is a sign of respect, so that he doesn't have to talk to him.