Deunan Knute is the central protagonist of the Appleseed franchise. Born near Los Angeles, California, in 2105, she is the daughter of Gilliam Knute, the scientist who invented the Bioroid race, and Carl Knute, a distinguished war veteran and police tactical officer. Her heritage is a mix of Scandinavian, French, and Sudanese descent. Deunan's childhood was marked by tragedy when she witnessed her mother's murder, an event that caused traumatic memory loss. The specifics of this incident vary across different adaptations, ranging from an accidental shooting in a laboratory to a deliberate assassination by a sniper. Following this loss, her father trained her extensively in combat and strategy from a young age. She eventually joined the LAPD SWAT unit, where she met and began a relationship with her future partner, Briareos Hecatonchires. When World War III broke out, both were conscripted into the US Army and served together on the North African Front. After Briareos was presumed dead and the United States dissolved, Deunan led a band of mercenaries in Europe before being recruited into the utopian city of Olympus by its elite ESWAT (Extra Special Weapons and Tactics) unit.

Deunan is known for a fiery and professional personality. While she has a tendency to occasionally break ranks, she is widely respected by her colleagues for her acumen and professionalism. She is characteristically warm and friendly with close associates like Briareos and the Bioroid Hitomi, but she can be aloof and antagonistic toward others, including authority figures like Commander Lance and the Seven Elders. A quick learner and a perfectionist, she exhibits strong feminist and independent traits, and she enjoys socializing with colleagues, wearing Prada clothing, and riding her high-end Coscom motorbike, being a Moto-GP enthusiast. Despite her tough exterior, she shows signs of vulnerability, including a poor tolerance for alcohol and symptoms of post-traumatic stress disorder after integrating into Olympus, though she becomes more stable over time.

As a soldier, Deunan's primary motivation is to navigate the complex political and social landscape of Olympus, a city where humans and engineered beings called Bioroids coexist. Her role is often that of a protector and a truth-seeker, uncovering conspiracies related to her mother's legacy and the future of humanity. She is frequently caught in the middle of conflicts between human factions who resent the Bioroids and the city's governing elders who propose replacing humanity entirely. Her personal motivation is deeply tied to her partner, Briareos, and her quest often forces her to confront her past and her feelings of loss and loyalty.

Her most significant relationship is with Briareos Hecatonchires, her lover and tactical partner, who is a highly modified cyborg. Their bond is the emotional core of the story, and his survival and transformation are pivotal to her character arc. In the film Ex Machina, this relationship is tested when Deunan is partnered with Tereus, a Bioroid clone created from Briareos's original human DNA. Initially resistant and confused due to Tereus's resemblance to her partner's former self, she gradually learns to accept him as an individual, which strains but ultimately does not break her relationship with Briareos.

Deunan Knute is an exceptionally skilled warrior. Having spent most of her life in combat, she is a specialist in weapons handling, explosive device manipulation, and hand-to-hand combat. Her gun-handling skill easily rivals that of her cybernetically enhanced colleagues, and she is noted as being a cunning strategist who can turn the tide of a simulated battle against superior numbers within minutes. She is also an excellent pilot of Landmates, the large, mechanized exoskeletons used in warfare, and she often customizes hers to her specifications. According to the Appleseed Databook, she is trained to be ambidextrous. She typically favors weaponry from the Seburo company, such as automatic handguns. Deunan also possesses implants in her vascular system that augment her immune system, ward off poisons, and can wake her from unconsciousness using powerful stimulants.