Samantha "Sam" Carr was James Wilson first wife from 1990 to 1991 when he was in the last two years of medical school. She is portrayed by actress Cynthia Watros in Season 6, although she is mentioned in Frozen, Birthmarks and Locked In. (although only as the first Mrs. Wilson) and is named for the first time in Lockdown. She and Wilson start dating again in Knight Fall. In Small Sacrifices they officially broke up hours after Wilson proposed to Sam for the second time.
She is a radiologist. The hospital she works at is currently unknown.
In Lockdown, Wilson tells Thirteen that he was married to Sam from 1990 to 1991. However, in Knight Fall, they seem to talk about being married about 12 years ago and that the breakup was "almost a decade" ago. The characters make it clear that she was married to Wilson before he met House.
In Frozen, House is trying to find out who Wilson is dating because he thinks it is someone they both know. House tells Wilson he has called all of his ex-wives. However, in Knight Fall, House apparently meets Sam for the first time and doesn't recognize her at all. However, it's clear he knew the name of Wilson's first wife, although she used "Samantha" at the time.