Vincent Anton Freeman
Vincent Anton Freeman is the protagonist of Gattaca. He, unlike most of his generation, was conceived without genetic selection, and is therefore at risk for many disorders and has a shortened life expectancy. Vincent dreams of becoming an astronaut, but knows his genetic inferiority makes this dream almost unattainable. He therefore does the only thing he can think of that will help him attain this dream: posing as a different individual with a better genotype. Vincent buys DNA from someone who is genetically superior and passes himself off as a "valid." He is ultimately granted his chance to live his dream when the doctor in charge of genetic screenings fakes his genetic validity because he wants to see if Vincent is able to go beyond his physical limitations.
Irene Cassini
Irene Cassini is a worker at Gattaca and Vincent’s love interest. She is technically not genetically “invalid”; however, she has an increased risk of heart failure which lessens her chances of participating in a mission. Irene is initially unaware that Vincent is posing as someone else, but he later shares this information with her, and she cooperates with him to deceive the rest of Gattaca.
Jerome Eugene Morrow
Jerome Eugene Morrow is the individual whom Vincent is posing as using samples of hair, blood, urine, etc. Once an accomplished swimmer, Jerome became depressed after placing second in a competition, and attempted suicide by jumping in front of a car, leading to his paralysis. The incident occurred abroad and is unrecorded; therefore, Jerome’s nearly-flawless genotype is ideal for deceiving Gattaca.
Anton Freeman
Anton Freeman is Vincent’s brother. He was conceived using genetic selection, unlike his brother. However, instead of becoming an astronaut, Anton becomes a detective, and works on the case which comes close to exposing his brother as an impostor. Upon discovering the truth, Anton warns his brother of the illegality of his actions, but does not expose him. Swimming competitions at the beach between Anton and Vincent become an important source of symbolism throughout the film.
Director Josef
Director Josef is a Gattaca worker and, it transpires late on in the film, the Mission Director's murderer. The case comes close to exposing Vincent’s true identity, but Director Josef’s confession clears his name.
Dr. Lamar
Dr. Lamar is a doctor at Gattaca in charge of administering blood and urine tests to Vincent (as Eugene) and other Gattaca workers. Dr. Lamar later reveals that he knows Vincent has been using Eugene’s samples to pose as a “valid,” but he does not expose Vincent. He says that his son admires Vincent and expresses his hopes that his son, who does not have a superior genotype, will still be able to achieve his goals.
Marie and Antonio Freeman
Marie and Antonio Freeman are Vincent and Anton’s parents. They conceive Vincent naturally (without using genetic selection), but regret their decision upon hearing the disorders their son is at risk for, and choose to conceive their second son using genetic selection. Anton, being genetically superior, is deemed worthy of inheriting his father’s name.
Detective Hugo
Detective Hugo is employed to track down the Mission Director's murderer at Gattaca. He works alongside Anton Freeman during the case. During their search, and under Hugo's watch, an invalid's unaccounted-for eyelash is found. This leads to a manhunt for the invalid, with Hugo making him the main suspect. It's Hugo that believes the suspect may be working at Gattaca under false pretenses—'a borrowed ladder'—and so insists on testing the entire Gattaca staff with 'blood from the vein.' When all his leads fail, he becomes frustrated and even insinuates that Director Josef might have had something to do with it, saying: "the mission means a great deal to you, doesn't it? And your late colleague opposed it..." Despite being wrong about the invalid murderer, Hugo is right that the invalid is working as a borrowed ladder and, however briefly, sniffs out Director Josef's involvement in the death before anyone else.
Head Janitor
The head janitor is Vincent's boss when he first arrives at Gattaca. He teases Vincent for his ambition of going into space on a mission. "When you clean the glass," he tells Vincent, "don't clean it too well...You might get ideas."
When Vincent—now Jerome—becomes a Gattaca employee, he meets his former boss on the stairs, and we see a completely different side to this old man. He is entirely deferential; he takes Jerome's cup and says "I'll take care of that for you, Mr. Morrow." It must be noted, however, that when Detective Hugo next finds a sample for the invalid suspect, it is on a cup that looks suspiciously like the one the Head Janitor takes from Jerome. Perhaps he suspects him and hands the cup to the detectives?
The head janitor's apparent personality shift speaks volumes about the world in which Gattaca is set. He believes wholeheartedly in the status system in play and so, when he knows Vincent for an 'invalid,' he treats him with ridicule and scorn. But when Vincent is disguised as a 'valid', he gives him status, and demotes himself accordingly. There is something tragic about this absolute belief in how people in the society are defined. He is unable to see Vincent for who is actually is, and can only see what others say about him: that he is either an 'invalid' or a 'valid'.
German
German is employed—illegally—by Vincent to find a 'valid' he can pose as. German is thrilled to have found such a good match; a man whose "credentials are impeccable," with "an expiration date you wouldn't believe." German very simply views Jerome Morrow as a series of statistics, and impressive ones at that. He is aware of the irrelevance in this society of what one looks like when one has access to genetic information. When questioned about whether Vincent and Jerome look similar enough, he responds: "It's close enough. When was the last time anyone looked at a photograph? You could have my face on your name tag for Christ's sake." He sets Vincent and Jerome up (and takes 20% of Vincent's payment to Jerome as a fee) and thus starts the main element of the plot rolling.
