Abby Mills - The Good Girl
Abby 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. When she is back on the island, she attempts to reconcile with her father and her former boyfriend Jimmy.

Henry Dunn - The Groom
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.

Patricia "Trish" Wellington - The Bride
Trish Wellington is Henry's bride-to-be. She loves Henry and wants to marry him but her father disapproves of Henry. The Wellingtons are wealthy, so Trish's perfect wedding comes in the form of a grand week-long stay on Harper’s Island, full of activities, food and fun for her family and friends. Trish loves her father and sister very much, as well as Henry, unlike her father.

Chloe Carter - The Flirt
Chloe Carter is one of Trish's bridesmaids[4] and Cal's girlfriend. She is sexy,[4] flirty, impulsive, and always looking for ways to live life to the fullest, and has a surprising curiosity for serial killers, including John Wakefield. She's an intelligent woman searching for romance and love. At first her relationship with her boyfriend Cal seems shallow; she's an outgoing flirt and has attracted the interest of both Sully and Marty. However, later events make it clear that Chloe's feelings for Cal are genuine. In episode 11, Cal rescues her and proposes marriage, and she accepts.[6]
DEATH – In Episode 11, mere moments after getting engaged, Cal and Chloe find themselves trapped by Wakefield at a dead end in the middle of a bridge. Cal tries to hold Wakefield off so Chloe can try to climb to safety, but is stabbed and thrown into the river below. Rather than try to get away, she denies Wakefield the chance to kill her and instead lets herself fall from the bridge, telling him, "You can't have me."[6]
Appearances: Episodes 1–4, 6, 8–11, 13
Committed suicide.

Cal Vandeusen - The Outsider
Cal Vandeusen is a doctor and Chloe’s boyfriend. He is a charming British outsider who doesn't know anyone in the wedding party, but tries to fit in with the tight knit groups. He treats Chloe like gold, and bought an engagement ring for her before entering Harper's Island. In Episode 10, the ring is given to Chloe before Cal leaves her to search for a boat. He is then shot in the shoulder and is in critical condition, relying on Sully to operate.[7] Miraculously, Sully manages to save Cal, and they both go after Wakefield to save Chloe.[6]

Jimmy Mance - The Old Flame
Jimmy Mance is a local fisherman and Abby's high school sweetheart. He's happy for the Wellington-Dunn wedding coming to Harper’s Island because it brings Abby back to the island. Abby and Jimmy rekindle their relationship shortly before the wedding guests are supposed to be sent home. In Episode 10, Jimmy is almost killed when the docks explode, but is spared because of Sheriff Mills' agreement with Wakefield to trade his life for Jimmy's, and is again spared during the Cannery massacre.[7] These events, along with a file on him in the Sheriff's attic, cause most of the survivors to suspect him of helping Wakefield.[2] In the series finale, Henry fakes Jimmy's death along with his own and Abby's, and tries to force him to sign a confession by threatening Abby. He tackles Henry off a cliff to protect Abby, but sustains only minor injuries. Jimmy, along with Abby, Shea and Madison, escapes the island.[3]

Sheriff Charlie Mills - The Sheriff
Sheriff Mills is the local sheriff of Harper’s Island and Abby's father. He supposedly killed John Wakefield seven years ago, but not before John Wakefield murdered his wife, Sarah. Sheriff Mills sent Abby away, and now that she’s back for the wedding on Harper's Island, he hopes to reconcile with her. But times have changed, and Sheriff Mills has some dark secrets he has no intention of sharing with his daughter. Sheriff Mills appeared on the 6th episode of Harper's Globe.

Thomas Wellington - The Father of the Bride
Thomas Wellington is Trish and Shea's father. He's also Katherine's husband. He's a conservative real estate mogul. He only wants the best for his daughter; but as far as he’s concerned that doesn’t involve marrying Henry Dunn. Mr. Wellington is accustomed to getting his way, and plans on stopping this wedding at all costs. He's also the only character that would have ever suspected Henry as the killer; in Episode 5, "Thwack", he admitted that he didn't trust Henry based on "gut instinct".

J.D. Dunn - The Black Sheep
J.D. Dunn is Henry’s adoptive brother. He’s a dark and brooding loner with tattoos all over his body that speak more to his true nature than he ever lets on in conversation. Being the only brother of the groom should have made him a lock for “best man,” but J.D.’s barely a guest at the wedding and wouldn’t mind just missing it all together. His childish antics make Henry’s life more difficult, and sometimes there’s a malevolence in them that makes everyone wonder if J.D. has some secret endgame. He's arrested as a murder suspect in Episode 8, and tells the Sheriff where to find Cole Harkin, who he was helping track the copycat killer. He escapes later the same episode when the police station is attacked.

Christopher "Sully" Sullivan - The Best Man
Chris is Henry's best man. All of his friends call him "Sully". He's a fun-loving frat boy at heart whose good buddies live vicariously through his many sexual escapades. He's been Henry's best male friend since middle school. It's questionable if he's at the wedding more for Henry's benefit or for the bachelor party and bridesmaids, particularly when he gets an eyeful of Chloe. He is referred as the "team player" of his gang (consisting of him, Danny, Malcolm, Booth, and occasionally Abby and Beth). He attempts to attract Chloe into being with him instead of being with Cal. He unintentionally forgets to save Cal in Episode 2, who gets caught in a rope trap. Cal then takes revenge on Sully by throwing feathers on a honey-coated Sully (he was at the spa), which was so humiliating that even his own gang laughed at the joke. Although he initially wants to leave immediately despite the threat to Madison's life, in Episode 10, he volunteers to go with Cal to find a sailboat so everyone can escape the island, and when Cal is shot in the process, he takes him to the clinic and, under Cal's direction, manages to remove the bullet and save Cal's life. He later teams with Danny in an effort to save Chloe, and ambushes and shoots Wakefield while Danny acts as bait, but the others choose not to kill Wakefield. Sully says that it is a "big mistake". When Trish finds a boathouse, Sully stays in the boathouse to man the radio, and puts Shea and Madison on a small boat after Wakefield's escape, but chooses to stay behind to help his friends. He later goes with Henry to look for Trish, intending to find her and the others before heading to the marina to meet the Coast Guard.

Marty Dunn - The Uncle
Uncle Marty is a surrogate father to Henry – the only family besides J.D. that he has at the wedding. Uncle Marty loves being the center of attention; he started partying sometime in the `70s and just never stopped. But behind his blithe demeanor is someone that cares deeply for Henry, who would do anything to protect him. And behind that is a guy that pops pills when no one is looking while toting around a bag stuffed with bundles of cash and a gun. In "Sigh", Henry reveals that Marty wanted to use the money to invest Malcolm's brewery.

Hunter Jennings - The Other Man
Hunter Jennings was Trish’s ex-boyfriend from college. He’s from a family as affluent as the Wellingtons. He’s exciting and passionate. He’s also selfish and unreliable, which is why Trish broke up with him. But now that she’s getting married, Hunter has shown up (hired by Mr. Wellington) in the island even though he's not invited, hoping to convince Trish that he’s the one she should be marrying. A deleted scene on the series DVD has Katherine showing Thomas a file on Hunter, revealing the man has been disowned from his family for his thieving ways, making Thomas realize he may not be a good match for Trish after all.

Shea Allen - The Maid of Honor
Shea Allen is Trish's big sister and the Maid of Honor. From the outside, she appears to have it all – a great husband, a beautiful daughter, and all the money in the world. But nothing is at it seems. There are problems in her marriage and her daughter Madison is acting out. The stress of keeping up appearances has Shea trapped in a life she never wanted for herself. With the exception of a few locals, Shea and her daughter, along with Abby and Jimmy, are the only survivors of the Harper's Island murders.

Richard Allen - The Brother-in-Law
Richard is Shea's husband, a guy who married into the Wellington family and business and lives everyday with that fact hanging over his head. Henry sees Richard as an example of what not to become – a meek subordinate who has completely broken under the thumb of Mr. Wellington. Richard keeps his severe contempt for Mr. Wellington under wraps, but is already in the process of taking revenge on the man who has made his life so miserable. In Episode 3, it's revealed that he was having an affair with Katherine Wellington. Trish sees him with Katherine and reveals their betrayal to her father during an argument, but Mr. Wellington decides to do nothing until after Trish's wedding.

Madison Allen - The Flower Girl
Madison is Shea and Richard's daughter. She's cute, sweet, and sometimes, horribly spooky. Lots of kids enjoy mischief but Madison might enjoy it a little too much. She has a tendency to say things that indicate she has a better idea about what's happening on Harper's Island than the adults do. Madison was kidnapped by Wakefield through episodes 8 and 9, though she tells Abby that it was the Sheriff who abducted her. In episode 10 she tells Trish that she lied, claiming that Wakefield told her that if she didn't, her mother would "disappear" like her father. Madison later tells her mother and Trish that she first met Wakefield, her "new friend", the day they arrived on the island. Both Madison & her mother survived the series and left the island.

Katherine Wellington - The Stepmother
Katherine is the very definition of a trophy wife; a woman closer in age to her stepdaughters than her husband. Trish resents her, but Shea tolerates her because she makes their dad happy. But considering Katherine's secret dark desires, that might not be for long. In Episode 3, it's revealed that she was having an affair with Richard Allen. According to producers a sub-plot was meant to be included that Thomas had lost all his money through a bad business deal and that it was Katherine that was paying for the entire wedding, but she allowed Thomas to pretend he was doing it so he did not lose face in front of his daughters. The storyline was dropped due to time constraints.

Danny Brooks - The College Buddy
Danny is a groomsman and one of Henry's best friends from college. He's the sensitive guy in the group. He's thoughtful and always wants to do the right thing. Danny feels things deeply, and when he senses injustice, he can't walk away, but has to try and make things right. He is mainly the closest friend of Sully, but is still close to Malcolm and Booth. He is kind enough to attract many friends, which Sully envies. In Episode 12, he acts as bait for Wakefield so Sully can ambush and shoot him.

Malcolm Ross - The Hustler
Malcolm Ross is a groomsman. He's a big, boisterous guy who not only brings his own beer to a party, but he brews it himself. Malcolm is trying to start up a business to mass-produce his microbrew, Sacred Turtle. Even though his friends are very supportive emotionally, he lacks the funds to finance his endeavor. His inability to raise capital has put a great deal of stress on Malcolm, and made him desperate enough to do things his friends would never suspect. Among his friends, Booth is the one he is closest to.

Joel Booth - The Nerd
Joel is a groomsman. Everyone calls him by his surname, Booth. He's a loyal friend who lacks some of the social graces of the other groomsmen. His hypochondria amuses his friends to no end. He can be very jumpy and panicky, although his decisions are usually for the best.

Beth Barrington - The Single Girl
Beth Barrington is a bridesmaid and Trish's former college roommate. She's beautiful, energetic and athletic. Though she didn't grow up as privileged as Trish, she's very comfortable in that world. She also said she wants to find love with as good a man as Henry. She develops a quick friendship with Malcolm throughout episode 6 and 7 after Malcolm comforts a traumatized Beth.
DEATH – In Episode 9, after a long search of an underground tunnel system sparked by a trail of blood and Beth missing, Beth's body is discovered by Danny; her body had been cut in half by Wakefield. Her top half and right arm was shown, but the bottom half and left arm was never found or shown.
Appearances: Episodes 1–9
Killed by John Wakefield.

Lucy Daramour - The Socialite
Lucy is a bridesmaid and one of Trish's childhood friends. Their families traveled and summered together. Though Lucy is more of a socialite than the other bridesmaids, she's trying to find her own way in the world by attending law school. Lucy is always carrying her handbag dog, Gigi. She also has a boyfriend named Ryan.

Shane Pierce - The Townie
Shane is a local fisherman who pretty much dislikes everyone. He works on a boat with his best friend, Jimmy Mance, and hates that the return of Abby Mills has turned Jimmy into her little whipping boy. He has a particular distaste for Henry Dunn's brother, J.D., especially after J.D. starts flirting with his ex-girlfriend, Kelly. Shane's got a short temper and a history of violence, which makes him capable of just about anything.

Kelly Seaver - The Outcast
Kelly has a unique connection with Abby: both of their mothers were killed by John Wakefield. But when Abby left the island, Kelly stayed behind and has never gotten over her mother's murder. She's struggled with depression and suicide attempts and a secret belief that John Wakefield is still alive and coming back for her.

Nikki Bolton - The Biker Chick
Nikki is an old friend of Abby's and a local who lives on the island and manages The Cannery, a bar on the island. She's a tough, sexy, straight-talking local who doesn't back down from confrontation. She's thrilled Abby's back on the island, and looks forward to having fun while the wedding party's in town. A good friend of Kelly's, she is the one to find her body, but is otherwise nearly completely excluded from major events. She manages to walk into the Cannery unimpeded, which convinces Maggie the killer isn't after locals, and gives the others her keys so Sully and Cal can use her car to go get the sailboat. Nikki shares a kiss with Sully before he leaves with Cal, but any potential relationship ends with her death at Wakefield's hands.

Ike Campbell - The Doctor
In Episode 3, Doctor Campbell carries out a post-mortem on Kelly Seaver, attempting to determine whether she committed suicide or was murdered. He also investigates the deaths of Reverend Fain and Thomas Wellington, remarking about how similar they are to the Wakefield killings. Sheriff Mills reminds him that John Wakefield is dead, but Doctor Campbell replies that someone is doing, "one hell of a job imitating him!" He reminds Sheriff Mills that the head spade, used in several killings, was Wakefield's signature weapon. It is possible the Doctor survived the Wakefield-Dunn killing spree, though his fate is not revealed on-screen; he may be among the "handful of locals" referred to by FBI Agent Hanson as having survived the killings.[3]

Reverend Fain - The Preacher
Was supposed to officiate at Henry and Trish's wedding

Deputy Garrett - The Guard
The deputy helps with investigating the murders on the island. He's also the jail guard at the police station.

Deputy Patrick Lillis - The Deputy
Deputy Lillis is one of Sheriff Mills' deputies and is the nephew of the Sheriff's best man at Sheriff's wedding. Deputy Patrick Lillis joined Sheriff Mills to investigate Nikki Bolton's call about Kelly's suicide. He later was sent to investigate the disappearance of Reverend Fain. He found the Reverend's hearing-aid in the woods, before he and Sheriff Mills discovered his dismembered body in the swamp. He also joined the other deputies in tracking J.D. in the woods.

John Wakefield - The Legend
John Wakefield was the perpetrator of a killing spree in 2001 on Harper's Island and the series' main antagonist. He originally killed six and wounded five in various locations on the island. The victims were stabbed, disembowelled, and then burned, with three bodies hanged from the Tree of Woe. The surviving victims all sustained severe burns. Wakefield grew up in Tacoma, Washington. He was a fisherman that frequented the waters off of Alaska and Washington.
During a stay on Harper's Island in the 1980s, he was arrested for one count for attempted murder of a police officer and was given a life sentence. He was held at a maximum security prison in upstate Washington. Wakefield was released in 2001 for "good behavior", after completing only 17 years of his sentence. Wakefield soon returned to Harper's Island, where it's believed he went on a murderous rampage.
After the murders, it's believed that Sheriff Charlie Mills shot and killed Wakefield, but recent photographs that match up almost identically to Wakefield's figure suggest otherwise.