Howard Roark is a staunch loner and individualist. He would rather starve than compromise his personal or professional integrity as an architect. He has no use for public opinion or those who control it. He is tall, with red/orange hair, physically strong and maintaining only mastery of himself. Roark endures every shift of fashion. The narrator says that "His face was like a law of nature ... a contemptuous mouth, shut tight, the mouth of an executioner or a saint." As Mallory observes to Dominique, "One can imagine him [Roark] existing forever."
Toohey is described as the ultimate "second-hander." He is a parasitic "non-entity" in direct opposition to Roark. Toohey's goal is to bring everyone in the world down to the same common denominator and worship the self-sacrificing attitude, which he says brings peace and happiness. He avoids direct contact with people (like Roark) while working behind the scenes to destroy them.
Dominique's physical image is delicate and slender. She wears elegant clothes and expensive jewelry that emphasize her long legs ending in high heels with pointed toes. Her eyes are cold, and her hair is yellow, close-cropped to her face. However, this is only her outward appearance. Dominique is deliberately self-destructive. She puts herself through emotional and physical tests to prove endurance and strength of both spirit and body. She declares, "I take the only desire one can really permit oneself. Freedom."
Keating is the tragic character of this book. He undergoes the most dramatic change as everything he believes to be true turns out to be an illusion. Keating starts out as a very handsome young man, filled with the eager idealism of making his mark on the world. People are attracted to him, and he learns how to make a high-profile image of himself to fulfill the high expectations of his every success. Keating is, however, insecure and consistently looks to the opinions of others (notably Roark) for confirmation of his self-worth. By the end of the book, Keating is a used-up "has-been" and one of Toohey's helpless victims.
Wynand is, like Roark, possessed of strength of mind and body. He grew up poor in New York City's Hell's Kitchen and survived to found a vast empire, including mass-media newspapers.
Catherine is the direct opposite of the coldly frank and intellectual Dominique. She is warm, loving, caring and devoted to Keating. Like Keating, Catherine changes over the course of the story. She is so entirely susceptible to suggestion that she devotes herself to a noble cause, making of it her life's work under the influence of her Uncle Toohey.