V is a masked anarchist who seeks to systematically kill the leaders of Norsefire, a fascist dictatorship ruling a dystopian United Kingdom. He is well-versed in the arts of explosives, subterfuge, and computer hacking, and has a vast literary, cultural and philosophical intellect. V is the only survivor of an experiment in which four dozen prisoners were given injections of a compound called Batch 5. The compound caused vast cellular anomalies that eventually killed all of the subjects except V, who developed advanced strength, reflexes, endurance and pain tolerance. Throughout the novel, V almost always wears his trademark Guy Fawkes mask, a shoulder-length wig of straight dark-brown hair and an outfit consisting of black gloves, tunic, trousers and boots. When not wearing the mask, his face is not shown. When outside the Shadow Gallery, he completes this ensemble with a circa-17th century conical hat and floor-length cloak. His weapons of choice include daggers, explosives and tear gas.
The book suggests that V took his name from the Roman numeral "V", the number of the room he was held in during the experiment.
Evey "Eve" Hammond is a sixteen-year-old (seventeen-year-old as of Book 2) whom V saves from the Fingermen. The novel details her life's story: how she lost every person she ever loved due to the Norsefire party and its criminal connections, how she met V and grew to understand him and, finally, how she became his successor.
Adam Susan, also known as the "Leader", is the dictator of the Norsefire Party and its functions, although some of his power is ceremonial. Susan is in love with Fate (a computer system) and prefers its cold, mathematical companionship to that of his fellow human beings. Susan also expresses a solipsist belief that he and God (referring to the Fate computer) are the only truly "real" beings in existence, though he also believes that he must devote his life to leading his people. He is an adherent of fascism and racist notions of "purity", and genuinely believes that civil liberties are dangerous and unnecessary. He appears to truly care for his people, however, and it is implied that his embrace of fascism was a response to his own loneliness. Before the War, he was a Chief Constable. He is assassinated by Rose Almond, the widow of one of his former lieutenants.
Eric Finch is the chief of New Scotland Yard and Minister of Investigations, which has become known as the Nose. Finch is a pragmatist who sides with the government because he would rather serve in a world of order than one of chaos. He is nevertheless honorable and decent, and the Leader trusts him as reliable and lacking ambition. He eventually achieves his own anagnorisis and self-knowledge, expressing sorrow over his complicity with Norsefire's atrocities.
- Rosemary "Rose" Almond: The abused wife of Derek Almond. When her husband is murdered, Rose becomes depressed and must turn to Roger Dascombe (whom she strongly dislikes) for company and support. After Dascombe is also killed (also at the hands of V), she is forced to become a showgirl as a means of supporting herself. After V shuts down the surveillance systems, she uses the opportunity to buy a gun and assassinate Adam Susan. She is last shown in an interrogation conducted by the Finger and her fate is unknown. She is the only supporting character who at one point in the story drives the narrative through an inner monologue, which besides her is only done by V, Evey, Adam Susan and Finch.
- Dominic Stone: Inspector Finch's partner and protegé. Dominic is the one who figures out the connection between V and the former Larkhill camp staff and V's hacking into the Fate computer system. Very much like Finch, he only works as an officer in the Nose due to a sense of dedication to his country and not due to any political affiliation to the Norsefire Party. At the end, Evey rescues Dominic from a mob and takes him to the Shadow Gallery where it is implied she will train him as her successor after she has taken the persona of V.
- Gordon: A petty criminal specialising in bootlegging. After V abandons Evey during Book 2, Gordon takes her in as an act of kindness after he catches her stealing from his home and the two eventually become lovers. He is murdered by Alistair Harper, a ruthless gangster who is trying to expand Scotland's organised crime syndicate into London.
- Peter Creedy: A coarse, petty man who replaces Derek Almond as the security minister of the Finger after the latter's death. He aims to replace the weakening Susan as Leader, but as part of Mrs. Heyer's plot, Alistair Harper's thugs kill him (Creedy had hired the thugs to bolster the weakening Finger, but Helen Heyer offered them more).
- Helen Heyer: The ruthless, scheming wife of Conrad Heyer. She uses sex and her superior intellect to keep her husband (for whom she feels nothing but contempt) in line, and to further her own goal of controlling the country after he becomes Leader. At the same time, she sleeps with Harper and turns him against Creedy. Her master plan collapses and she is last seen offering her body in exchange for protection and food to a semi-drunken gang after being rejected by Finch (who she hoped would join her in taking over what was left of the Party after her husband, Peter Creedy and Alistair Harper are all killed) and after anarchy has spilled into London.
- Conrad Heyer: In charge of "The Eye" — the agency that controls the country's CCTV system. His wife Helen dominates him, and she intends for him to become leader, leaving her as the power behind the throne. V sends Conrad a videotape of Helen being unfaithful and he snaps, killing her lover Alistair Harper but sustaining a fatal wound from Harper's straight-edge razor in the process. When Helen learns what he has done, she is enraged at the destruction of her plans and leaves him to bleed to death, setting up a video camera connected to their TV so that he can watch himself die.
- Lewis Prothero: The former Commander of Larkhill, the concentration camp that once held V. He later becomes The Voice of Fate, the government radio broadcaster who daily transmits "information" to the public. V stops a train carrying Prothero and kidnaps him. He is driven insane by a combination of an overdose of Batch 5 drugs and the shock of seeing his prized doll collection burned in a mock recreation of Camp Larkhill in V's headquarters. He remains incapacitated for the rest of the story.
- Bishop Anthony Lilliman: The voice of the Party in the Church. Lilliman is a corrupt priest who molests the young girls in his various parishes. Like Prothero, he worked at Larkhill before being given a higher employment by the state. Lilliman was a priest who was hired to give spiritual support to the prisoners being given Batch 5 drugs. He is killed after he almost rapes Evey Hammond (who is dressed up as a young girl), when V forces him to take communion with a cyanide-laced wafer.
- Dr. Delia Surridge: Larkhill camp doctor whom V kills by lethal injection of an unspecified drug. Surridge (the only one of V's former tormentors who feels remorse for her actions) apologises to him in her final moments of life. Finch also mentions that he has feelings for her, and he feels maddened at her death and determined to end V's life.
- Derek Almond: A high-ranking official of the Norsefire government. He ran the government's secret police force, known as The Finger. Almond is warned by Finch that Surridge will be the last of V's targets and goes to her house to prevent him but is killed by V. Almond is replaced by Peter Creedy. His death sets in motion one of the novel's major story arcs; that of his widow, Rose, who is left penniless and traumatised by the loss of her husband, who was cold and abusive toward her but whom she nevertheless loved. In her grief and desperation, she blames her plight on Norsefire's leader, Adam Susan, and assassinates him at the novel's climax.
- Valerie Page: A critically acclaimed actress who was imprisoned at Larkhill when the government found out she was a lesbian. Her tragic fate at the hands of the regime inspires V to fight against Norsefire.
- Roger Dascombe: The technical supervisor for the Party's media division and the Propaganda Minister of The Mouth. In the first scene with him, he is presented as being openly effeminate. After Derek Almond's death, Dascombe sets his sights on his widow, Rosemary, who eventually turns to him for support. During V's attack on Jordan Tower, he is set up as a dummy V and killed by the police.
- Alistair "Ally" Harper: The Scottish organised crime boss who kills Evey's lover Gordon. Initially Creedy hires him and his men to temporarily bolster the police force after V destroys the government's surveillance equipment, but Helen Heyer recruits him to her side to ensure Creedy's downfall by offering to place him in charge of the Finger after Conrad comes to power. He temporarily becomes Helen's lover. After Creedy's takeover, Ally fulfills his end of the bargain with Helen and kills Creedy with a lethal slash from his straight razor. Conrad beats Harper to death with a wrench as Ally fatally slices his neck.