Dr. Malia Waincroft was a pediatric oncologist employed at Honolulu Hospital, and the wife of Chin Ho Kelly.
Malia and Chin Ho Kelly were originally engaged before the events of the pilot, but the couple separated during Chin's investigation by Internal Affairs. It was assumed by Chin's family that Malia had been the one to initiate this, when it was actually Chin's idea to break off their relationship.
Malia wore her engagement ring on a chain around her neck during Season 1. In Season 2, Chin and Malia reconnected and during the episode Kil'ilua, Chin proposed to Malia a second time and she accepted. Later, while the team were fleeing North Korea after rescuing Steve from Wo Fat, Chin told them that he was getting married and he asked Steve McGarret to be his best man.
The couple were eventually married in Alaheo Pau'ole with Kono Kalakaua as one of Malia's bridesmaids, while Danny Williams and Kamekona Tupuola were Chin's groomsmen. For a year and a half, Chin and Malia lived a happy life together up until the Season 2 finale episode, Ua Hala, when Malia was taken hostage as part of a plot to free crooked cop Frank Delano from Halawa Correctional Facility. Although Chin co-operated, and chose to save Malia instead of Kono, Delano instructed his accomplice to shoot Malia anyway. She was left to bleed to death on the kitchen floor for Chin to find.
In the Season 3 premiere episode, La O Na Makuahine, paramedics tried to save Malia, but she was so severely injured that she eventually succumbed to her wounds and died, leaving Chin grief-stricken and completely devastated.
In the aftermath of Malia's death, Chin became obsessed with getting revenge against Delano and later succeeded in doing so by shooting Delano dead in cold blood in a underground parking lot.
In Kanalua, the team attended Malia's funeral.
In Hana Lokomaika'i, it was revealed that Malia had a brother, Gabriel, who had been arrested 15 years before.