William Walker (deceased):Died of a heart attack in the first episode and was then discovered to have had a twenty-year affair, in which he fathered an illegitimate child, who turned out to not the one we thought it was.
Nora Walker (nee Holden):Widow of William. Democratic Apron Matron, with a Republican fetish.
Sarah Walker, formerly Whedon:Oldest of the five children. Working mom. She later becomes a single mom. Also ran the family business for a period of time.
Kitty McAllister WalkerThe next eldest Walker child. Republican political activist. Formerly a talk show host, but now wife and senior advisor to Senator Robert McAllister (R-CA). The Senator ran for President, but lost Super Tuesday and pulled out.
Tommy WalkerThe middle child. His wife had twins, but one died. The resulting post-natal depression resulted in his wife going to live with her parents and him cheating on her with his secretary. Then he stole money from the company
Kevin WalkerThe gay one, now married to Scotty, a chef.
Justin WalkerFormerly with a drug habit, he had signed up for the American Armed Forces just after 9/11 and served in Afghanistan. When he was called back for active duty in Iraq, the family attempted to get him out of it until Justin decided he would go. There he got an unspecified leg injury via IED and picked up the drug habit again during recovery. The habit has now mostly gone after a stint of home rehab- he's a recovering addict.
Rebecca Walker (nee Harper)The aforementioned illegitimate child. Till it turned out she wasn't. Now married to Justin, who she'd earlier thought was her half brother.
Saul HoldenNora's brother. Came out as gay in season two. Discovered he was HIV-positive in the Season Four finale.
RyanThe new sibling, who thinks his mother killed himself when William tried to pay her off.
Senator Robert McAllister (R-CA)Kitty's husband. Has heart problems. Probably dead in a car accident.
Luc LaurentSarah's new French artist boyfriend.
Paige WhedonSarah's daughter.
Cooper WhedonSarah's son.