This is a list of fictional characters in the television series Harper's Island.
The Good Girl (Portrayed by Elaine Cassidy)
Abby Mills is Henry Dunn's best friend. She left the island seven years ago when her father, Sheriff Mills, sent her away after her mother was killed by John Wakefield, a scene she had witnessed. When she is back on the island, she attempts to reconcile with her father and her former boyfriend Jimmy. She usually hangs out with the groomsmen. Abby never wanted to return to the island after her father sent her away after the 2001 massacre, but still does so because of Henry and Trish's wedding. She is also good friends with Trish, especially after she helps her cope after her father's death. She is smart, strong, and brave, determined to protect her friends and stop Wakefield and finish the job that her father did not finish. She's initially suspected to be Wakefield's child based on an entry in his prison diary. That, along with the thought that the Sheriff is responsible for the murder and J.D.'s last words that it's all about her, causes others to partly blame her, until Madison tells the truth that the Sheriff is not the killer. It's eventually revealed that Henry is her half-brother, and is Wakefield's son and is working with his father to commit the murders. After Shea and Madison escape, Henry turns on Wakefield and kidnaps Abby and Jimmy, planning to frame Jimmy as Wakefield's accomplice and create his childhood fantasy life with Abby. She manages to engineer their escape by pretending to give in and slipping Jimmy a lock pick through a kiss before turning on Henry, and stabs Henry through the chest protecting herself and Jimmy. Henry's last words to Abby were that he loved her.
SURVIVAL – Abby, along with Jimmy, gets rescued by coast guards and taken to the mainland.
KILLS – Henry Dunn.
Appearances: Episodes 1–13
The Groom (29th victim) (Portrayed by Christopher Gorham)
He's Abby's long-time best friend. His parents' deaths several years earlier left Uncle Marty and J.D. as his only living relatives. In the second to last episode, he's revealed to be Wakefield's son, protégé (he was responsible for numerous deaths in Seattle, as practice), and accomplice, and Abby's half-brother. His motive is revealed to be his obsession with Abby; he loves her in his own twisted way, and is killing everyone around them in order to create a childhood fantasy life with her as he remembers Abby's wish that they could stay on the island forever, just the two of them. For most of the first part of the series, Henry deals with several problems such as proving himself to Trish's disapproving father, dealing with his suspicions about Hunter, and helping his friends do something about the blooded money they found. Henry acts as the survivors' unofficial leader, but has, in actuality, orchestrated the whole situation with his father and committed some of the murders. He turns on his father to protect Abby then kidnaps her and Jimmy and fakes their three deaths, planning to force Jimmy to sign a confession so Abby and he can live alone together on the island. Despite her reaction to his confession and previous escape attempt, he believes she shares his dream and takes her to say goodbye to Jimmy, which she does in order to slip Jimmy a lock pick. He lashes out at her when she rejects him, but Jimmy, who managed to free himself, tackles him off a cliff to protect Abby.
DEATH – In Episode 13, Henry comes up behind Abby when she is kneeling next to Jimmy at the bottom of the cliff, and she stabs him with the boarding knife out of protection and surprise. Henry's dying words were, "Abby... I love you."
KILLS – Ben Wellington, Reverend Fain, Hunter Jennings, Thomas Wellington, Richard Allen, Malcolm Ross, J.D. Dunn, Katherine Wellington, Trish Wellington, Christopher "Sully" Sullivan, John Wakefield.
Appearances: Episodes 1–13