A vigilante who wears a white mask that contains a symmetrical but constantly shifting ink blot pattern, he continues to fight crime in spite of his outlaw status. Moore said he was trying to "come up with this quintessential Steve Ditko character—someone who's got a funny name, whose surname begins with a 'K,' who's got an oddly designed mask". Moore based Rorschach on Ditko's creation Mr. A; Ditko's Charlton character The Question also served as a template for creating Rorschach. Comics historian Bradford W. Wright described the character's world view "a set of black-and-white values that take many shapes but never mix into shades of gray, similar to the ink blot tests of his namesake". Rorschach sees existence as random and, according to Wright, this viewpoint leaves the character "free to 'scrawl [his] own design' on a 'morally blank world'". Moore said he did not foresee the death of Rorschach until the fourth issue when he realized that his refusal to compromise would result in him not surviving the story.

A retired superhero who utilizes owl-themed gadgets. Nite Owl was based on the Ted Kord version of the Blue Beetle. Paralleling the way Ted Kord had a predecessor, Moore also incorporated an earlier adventurer who used the name "Nite Owl", the retired crime fighter Hollis Mason, into Watchmen. While Moore devised character notes for Gibbons to work from, the artist provided a name and a costume design for Hollis Mason he had created when he was twelve. Richard Reynolds noted in Super Heroes: A Modern Mythology that despite the character's Charlton roots, Nite Owl's modus operandi has more in common with the DC Comics character Batman.[38] According to Klock, his civilian form "visually suggests an impotent, middle-aged Clark Kent."

A superpowered being who is contracted by the United States government. Scientist Jon Osterman gained power over matter when he was caught in an "Intrinsic Field Subtractor" in 1959. Doctor Manhattan was based upon Charlton's Captain Atom, who in Moore's original proposal was surrounded by the shadow of nuclear threat. However, the writer found he could do more with Manhattan as a "kind of a quantum super-hero" than he could have with Captain Atom. In contrast to other superheroes who lacked scientific exploration of their origins, Moore sought to delve into nuclear physics and quantum physics in constructing the character of Dr. Manhattan. The writer believed that a character living in a quantum universe would not perceive time with a linear perspective, which would influence the character's perception of human affairs. Moore also wanted to avoid creating an emotionless character like Spock from Star Trek, so he sought for Dr. Manhattan to retain "human habits" and to grow away from them and humanity in general. Gibbons had created the blue character Rogue Trooper, and explained he reused the blue skin motif for Doctor Manhattan as it resembles white skin tonally, but has a different hue. Moore incorporated the color into the story, and Gibbons noted the rest of the comic's color scheme made Manhattan unique. Moore recalled that he was unsure if DC would allow the creators to depict the character as fully nude, which partially influenced how they portrayed the character. Gibbons wanted to be tasteful in depicting Manhattan's nudity, selecting carefully when full frontal shots would occur and giving him "understated" genitals—like a classical sculpture—so the reader would not initially notice it.

One of two government-sanctioned heroes (along with Doctor Manhattan) who remain active after the Keene Act is passed in 1977 to ban superheroes. His murder, which occurs shortly before the first chapter begins, sets the plot of Watchmen in motion. The character appears throughout the story in flashbacks and aspects of his personality are revealed by other characters. The Comedian was based on the Charlton Comics character Peacemaker, with elements of the Marvel Comics spy character Nick Fury added. Moore and Gibbons saw The Comedian as "a kind of Gordon Liddy character, only a much bigger, tougher guy". Richard Reynolds described The Comedian as "ruthless, cynical, and nihilistic, and yet capable of deeper insights than the others into the role of the costumed hero." He attempts to rape the first Silk Spectre in the 1940s. Issue nine reveals that years later he fathered her daughter Laurie as part of a consensual sexual relationship.

Veidt believes that his vast intelligence obligates him to unite the warring modern world as Alexander the Great did in his time. When he comes to doubt the value of confronting street criminals in the face of greater crimes of the powerful and governments that go unpunished, he endeavors to study world politics, and concludes that nuclear war will bring the world to an end in just a few years, and plans to use such a catastrophe to save the world.
Ozymandias is politically liberal, supporting social causes and performing at a benefit for India, which has suffered famine. He believes that everyone is capable of great intelligence, if they choose to be, and that any problem can be solved with the correct application of human intelligence.

Ozymandias is shown to be very genial as noted by Hollis Mason. He demonstrates his sense of humor, joking around many times during his interview with Nova Express and his battle with Rorschach, Nite Owl and Silk Spectre. Ozymandias is also a vegetarian. His favorite companion is his genetically-engineered pet lynx, Bubastis.

The daughter of Sally Jupiter (the first Silk Spectre, with whom she has a strained relationship) and The Comedian. Of Polish heritage, she had been the lover of Doctor Manhattan for years. While Silk Spectre was based partially on the Charlton character Nightshade, Moore was not impressed by the character and drew more from heroines such as Black Canary and Phantom Lady.