|Date of Birth||Unknown|
|Last Appearance||The Good Parts|
|Occupation||Former Vietnam Solider|
|Number of episodes||-|
|Portrayed by||Toni Collete|
Buck is a loud and profane troublemaker, characterized by Collette as "the aggressive protector type, a man's man". He explains his lack of a penis by claiming that it was blown off in the Vietnam War. Buck has a gun named Persephone and sometimes goes to the shooting range with Max and Marshall. . Unlike Tara and the other alters, Buck is left-handed. He is a heavy drinker and smoker. He wears large glasses and a trucker hat. Buck is loud about his attraction to women, hitting on Kate's friends and claiming to have had sex with a waitress at the local bowling alley, who gave him crabs. In season two he embarks on a love affair with Pammy, the bartender at the pub Tara, Max, Charmaine and Neil sometimes attend. Buck was killed in the penultimate episode by Bryce. Buck sort of said goodbye to Max while wanting to drink one last beer before being killed by Bryce, failing to do the latter. In the final episode Buck is seen apparently alive in the back of Max's truck as he and Tara prepare to leave.
- Collette said that Buck is her favorite of the original four personalities "just because he's most challenging", though she has to "always be careful not to make him a stereotype."