As the protagonist of the book, Roark is an aspiring architect who firmly believes that a person must be a "prime mover" to achieve pure art, not mitigated by others, as opposed to councils or committees of individuals which lead to compromise and mediocrity and a "watering down" of a prime mover's completed vision. He represents the triumph of individualism over the slow stagnation of collectivism. He is eventually arrested for dynamiting a building he designed, the design of which was compromised by other architects brought in to negate his vision of the project. During his trial, Roark delivers a speech condemning "second-handers" and declaring the superiority of prime movers; he prevails and is vindicated by the jury.
The character of Roark was at least partly inspired by American architect Frank Lloyd Wright. Rand described the inspiration as limited to "some of his architectural ideas [and] the pattern of his career". She denied that Wright had anything to do with the philosophy expressed by Roark or the events of the plot. Rand's denials have not stopped other commentators from claiming stronger connections between Wright and Roark. Wright himself equivocated about whether he thought Roark was based on him, sometimes implying that he was, at other times denying it. Wright biographer Ada Louise Huxtable described the "yawning gap" between Wright's philosophy and Rand's, and quoted him declaring, "I deny the paternity and refuse to marry the mother."
Peter Keating is also an aspiring architect, but is everything that Roark is not. His original inclination was to become an artist, but his opportunistic mother pushes him toward architecture where he might have greater material success. Even by Roark's own admission, Keating does possess some creative and intellectual abilities, but is stifled by his sycophantic pursuit of wealth over morals. His willingness to build what others wish leads him to temporary success. He attends architecture school with Roark, who helps him with some of his less inspired projects. He is subservient to the wills of others: Dominique Francon's father, the architectural establishment, his mother, even Roark himself. Keating is "a man who never could be, but doesn't know it". The one sincere thing in Keating's life is his love for Catherine Halsey, Ellsworth Toohey's niece. Though she offers to introduce Keating to Toohey, he initially refuses despite the fact that such an introduction would help his career. It is the only exception to his otherwise relentless and ruthless ambition, which includes bullying and threatening to blackmail a sick old man and unintentionally causing his death. Although Keating does have a conscience, and often does genuinely feel bad after doing certain things he knows are immoral, he only feels this way in hindsight, and doesn't allow his morals to influence current decision making. Keating's offer to elope with Catherine is his one chance to act on what he believes is his own desire. But, Dominique arrives at that precise moment and offers to marry him for her own reasons, and his acceptance of the offer and betrayal of Catherine ends the potential of romance between them. His acceptance of Dominique's offer of marriage, which would help his career far more than a marriage with Catherine, is a quintessential example of his failure to stand up for his own convictions.
Dominique Francon is the heroine of The Fountainhead, described by Rand as "the woman for a man like Howard Roark." For most of the novel, the character operates from what Rand later described as "a very mistaken idea about life." Dominique is the daughter of Guy Francon, a highly successful but creatively inhibited architect. She is a thorn in the flesh of her father and causes him much distress for her works criticizing the architectural profession's mediocrity. Peter Keating is employed by her father, and her intelligence, insight and observations are above his. It is only through Roark that her love of adversity and autonomy meets a worthy equal. These strengths are also what she initially lets stifle her growth and make her life miserable. She begins thinking that the world did not deserve her sincerity and intellect, because the people around her did not measure up to her standards. She starts out punishing the world and herself for all the things about man which she despises, through self-defeating behavior. She initially believes that greatness, such as Roark's, is doomed to fail and will be destroyed by the 'collectivist' masses around them. She eventually joins Roark romantically, but before she can do this, she must learn to join him in his perspective and purpose.
The character has provoked varied reactions from commentators. Chris Matthew Sciabarra called her "one of the more bizarre characters in the novel." Mimi Reisel Gladstein called her "an interesting case study in perverseness" Tore Boeckmann described her as a character with "mixed premises", some of which were mistaken, and saw her actions as a logical representation of how her conflicting ideas might play out.
Gail Wynand is a wealthy newspaper mogul who rose from a destitute childhood in the ghettoes of New York City to control much of the city's print media. While Wynand shares many of the character qualities of Roark, his success is dependent upon his ability to pander to public opinion, a flaw which eventually leads to his downfall. In her journals Rand described Wynand as "the man who could have been" a heroic individualist, contrasting him to Roark, "the man who can be and is". Some elements of Wynand's character were inspired by real-life newspaper tycoon William Randolph Hearst, including Hearst's mixed success in attempts to gain political influence. Wynand is a tragic figure who ultimately fails in his attempts to wield power, losing his newspaper, his wife, and his friendship with Roark. The character has been interpreted as a representation of Nietzsche's "master morality", and his tragic nature illustrates Rand's rejection of Nietzsche's philosophy. In Rand's view, a person like Wynand, who seeks power over others, is just as much a "second-hander" as a conformist like Keating.
Ellsworth Monkton Toohey, who writes a popular art criticism column, is Roark's antagonist. Toohey is Rand's personification of evil, the most active and self-aware villain in any of her novels. Toohey is a socialist, and represents the spirit of collectivism more generally. He styles himself as representative of the will of the masses, but his actual desire is for power over others. He controls individual victims by destroying their sense of self-worth, and seeks broader power (over "the world", as he declares to Keating in a moment of candor) by promoting the ideals of ethical altruism and a rigorous egalitarianism that treats all people and achievements as equally valuable, regardless of their true value. As one reviewer described his approach:
Aiming at a society that shall be "an average drawn upon zeroes," he knows exactly why he corrupts Peter Keating, and explains his methods to the ruined young man in a passage that is a pyrotechnical display of the fascist mind at its best and its worst; the use of the ideal of altruism to destroy personal integrity, the use of humor and tolerance to destroy all standards, the use of sacrifice to enslave.
His biggest threat is the strength of the individual spirit embodied by Roark.
Rand used her memory of the British democratic socialist Harold Laski to help her imagine what Toohey would do in a given situation. New York intellectuals Lewis Mumford and Clifton Fadiman also contributed inspirations for the character.
- Henry Cameron: Roark's architect mentor and employer
- The Dean: The dean of the Stanton Institute of Technology architecture school
- Guy Francon: Dominique's father and Keating's employer and business partner
- Catherine Halsey: Keating's fiancee and Toohey's niece
- Austen Heller: An individualistic thinker who hires Roark and becomes one of his biggest allies.
- Lucius Heyer: The business partner of Guy Francon, who is indirectly killed by Keating's attempts at manipulation.
- Mrs. Keating: Keating's overbearing and manipulative mother
- Steven Mallory: A disillusioned sculptor who tries to kill Toohey but later regains his confidence with the help of Roark
- Alvah Scarret: Wynand's editor-in-chief
- John Erik Snyte: An employer of Roark's who uses a group of five designers to create a final sketch