Special Agent Dale Cooper (Kyle MacLachlan)
Agent Cooper from the FBI comes to Twin Peaks to investigate the mysterious death of high school student Laura Palmer. He discovers a much seedier -- and much weirder -- little town than what appears on the brochures. Despite the weirdness (or maybe because of it), he falls in love with the town, with the people, with the cherry pie, and with a "damn fine cup of coffee." As the original series ended, it was suggested that Cooper was trapped in the evil Black Lodge, though his final fate was never revealed.
Laura Palmer / Madeleine Ferguson (Sheryl Lee)
Laura Palmer's murder is the catalyst for the entire Twin Peaks franchise. She first appears wrapped in plastic at the edge of the river in the pilot episode. At first glance, Laura is the perfect girl next door. A high school student, homecoming queen, and volunteer, the investigation soon reveals a disturbing double life. She was a cocaine addict, occasional prostitute and fetish model, and was sexually abused as a child. She appears in flashbacks and dream sequences throughout the series. Sheryl Lee also played Laura's identical cousin, Madeleine Ferguson, who comes to town after Laura's death. Maddy is eventually murdered, just like her cousin.
Leland Palmer (Ray Wise)
Laura's father, Leland, is a respected attorney in Twin Peaks, but like everything in the town, it is all a facade. As the series goes on, he becomes more and more mentally unbalanced. It is revealed that Leland was raping his daughter, and he eventually killed her. But, he was possessed by a demonic entity that has been part of him off and on since childhood, known only as Bob. Leland (while possessed by Bob) also murders his niece, Maddy, likely because of her similarities to Laura. He is eventually arrested, and is murdered by Bob while in custody. Laura believes his actions weren't his own, and she welcomes her father into the afterlife.
Sarah Palmer (Grace Zabriskie)
Laura's mother, Sarah, has some unspecified psychic powers, allowing her to predict the future or see things that aren't actually there. She has visions that help in the investigation, and also can act as a conduit for the dead to speak through her.
Audrey Horne (Sherilyn Fenn)
Though Audrey goes to school with Laura, she doesn't consider her a friend. She is considered a troublemaker, and develops a crush on Dale Cooper, even helping him investigate Laura's murder by going undercover at the brothel/casino Laura worked at. In the final episode, Audrey is chained to a bank vault (protesting against deforestation) when a bomb goes off. Her fate is never specifically revealed.
Benjamin Horne (Richard Beymer)
Audrey's father, Ben is one of the two richest people in Twin Peaks. He's not a good man, and sets about romancing the other richest person in town, with the intent of being included in her will, then killing her to collect her property. One of the many businesses he owns is One Eyed Jack's, the brothel/casino that Laura Palmer worked in. Ben sees Laura as the daughter he always wanted - until he starts a torrid affair with the girl. Laura was planning on blackmailing him at the time of her death. He was briefly arrested for Laura's murder. A psychotic break led him to believe he was a Civil War general. When he comes out of it, he attempts to atone for his past misdeeds, including building a relationship with Audrey. He also reveals that an affair with Eileen Hayward means that her daughter, Donna, is biologically his own daughter. When Will hears this, he punches Ben, which causes him to crack his head open on the way to the floor. It is never specified if he survived.
Will Hayward (Warren Frost)
The doctor and coroner in Twin Peaks, Doc Hayward is close friends with the Palmers and can't perform Laura's autopsy. His eldest daughter, Donna, is best friends with Laura. As the original series ends, the normally calm Doc gets into a fight with Ben Horne, who may be Donna's biological father. Ben may or may not be dead, and Doc appears calm and collected at the series' end.
Bobby Briggs (Dana Ashbrook)
Bobby was Laura Palmer's boyfriend, but was secretly dating Shelly at the same time. Nevertheless, Bobby was jealous that Laura was secretly dating James Hurley. Though Bobby appeared to be the perfect "boy next door," he was selling drugs, which was the reason Laura was dating him.
Shelly Johnson (Madchen Amick)
A waitress at the local diner, Shelly dropped out of high school to marry her boyfriend, Leo. It soon becomes apparent that Leo is an abusive husband with a bad temper. Shelly secretly begins dating Bobby Briggs, who was Laura's boyfriend, and also sells drugs for Leo. When Leo finds out about the affair, he tries to kill Shelly, but Shelly escapes. Leo is then shot and ends up comatose, forcing Shelly to quit her job to care for Leo.
Norma Jennings (Peggy Lipton)
Norma owns the Double R Diner. Married to a convict and having an affair with her high school sweetheart Ed Hurley, she also cares for her younger sister, Annie Blackburn.
Ed Hurley (Everett McGill)
Big Ed Hurley is unhappily married to Nadine. He is responsible for the accident in which Nadine lost her eye, so the marriage is mainly one of guilt. He is truly in love with his high school sweetheart, Norma Jennings, with whom he has an affair - until her husband is released from prison. When Nadine regresses to being a teenager, and eventually "breaks up" with Ed, Ed resumes his affair with Norma. As the series ended, Ed and Norma were planning to marry - until Nadine regains her memory.
Nadine Hurley (Wendy Robie)
The wife of Big Ed, Nadine is known for her eyepatch, after she lost her eye in a hunting accident on her honeymoon. As the series opens, Nadine is obsessed with creating a silent drape runner, convinced it will be her ticket to fortune. It is a failure, and Nadine tries to commit suicide. The pills put her into a coma, and when she wakes, she believes herself to be a teenager again. She joins the high school wrestling team and "breaks up" with Big Ed (thinking they are only dating) in order to date the captain of the wrestling team. As the original series wrapped up, Nadine was hit on the head and forgot everything that happened since her suicide attempt.
James Hurley (James Marshall)
Nadine and Ed's nephew, James lives with them because of an unstable home life. He is Laura's secret boyfriend, but after she dies, he falls for Donna. When Maddy shows up, James develops feelings for her, but after she is murdered, James leaves town and gets involved with Evelyn Marsh and a plan to murder her husband. James finally gets away and decides to travel the world. Before he leaves, he returns to Twin Peaks to promise Donna he will come back for her.
The Log Lady (Catherine E. Coulson)
The character's real name is Margaret Lanterman, but everyone knows her as the Log Lady. She is the "town eccentric" who always carries a small wooden log like a baby. She claims to be able to speak to the log, and delivers clairvoyant messages on the log's behalf.
Deputy Tommy "Hawk" Hill (Michael Horse)
A Native American, Deputy Hill is often called "Hawk" because of his uncanny tracking abilities.
Agent Gordon Cole (David Lynch)
David Lynch himself plays Agent Cole, who is Agent Cooper's direct supervisor. He only appears in a few episodes, as a hard-of-hearing agent who gets a crush on Shelly, the only person he can hear properly.
Denise/Dennis Bryson (David Duchovny)
Dennis Bryson had to wear women's clothes in an undercover operation and found it relaxed him. He began wearing women's clothes all the time, and took the name Denise. Bryson came to Twin Peaks after Cooper is accused of malfeasance.
Annie Blackburn (Heather Graham)
Norma's younger sister, Annie grew up in Twin Peaks but after a failed love and a suicide attempt, she went to live in a convent. She comes back to town to see what the secular world can offer, and falls in love with Agent Cooper. The feeling is mutual. In the series finale, Annie has been trapped in the Black Lodge, and she and Cooper escape after he is possessed by Bob.
Ronette Pulaski (Phoebe Augustine)
Ronette was with Laura at the time of her death. She was also raped and beaten by Bob, but unlike Laura, Ronette survived.