Marty Seamus McFly is a confident 17 year old who attends high school and dreams of becoming a rock star. He also lives in a family with various personal issues. He is the youngest of three children of George McFly and Lorraine Baines-McFly. He has a brother, Dave McFly, and a sister, Linda McFly. Marty's girlfriend is Guest. Marty is shown to be disappointed by his family, particularly his wimpish father and alcoholic mother. He enjoys playing electric guitar with his group The Pinheads. He is also a talented skateboarder, often clinging onto the back of vehicles to gain extra speed when he is late for school.[34] He also proves to be an excellent pistol shot, a skill he has honed by playing shooting games such as Wild Gunman. His carefree attitude results in confrontations with his high school's vice-principal Mr. Strickland, who calls him a "slacker", comparing him to his father. After Strickland warns him against associating with Doc Brown and claims that no McFly ever amounted to anything, Marty shows determination, stating that he will change history. When confronted with a challenging circumstance, he often uses the catchphrase "This is heavy!" He frequently loses his temper whenever he is accused of cowardice. He frequently uses pop culture references. His clothing reflects the fashion of 1985. He wears a pair of Levi's jeans, paired with a buttoned shirt, a denim jacket with a puffer jacket on top and a pair of Nike Bruin shoes. In 1955, he wears a camp shirt, two-tone jacket and denim, later changing to a check jacket and tie. He stands at an athletic and short stature of 5 feet 4 inches (1.63 m). He has dark brown, tousled hair, expressive brown or blue eyes, and an energetic, youthful build typical of an active teenager. As a boyfriend he’s compassionate and often reckless on behalf of his partner. He’s also clingy, protective, but has the flaw of pride issues. Oh yeah, and he hates being called “chicken”.

Doctor Emmet Brown is a resident of Hill Valley, California. He was the inventor of the DeLorean Time Machine. A scientist by trade, Doc was a "student of all sciences" who spent much of his time inventing. He was the son of Judge Erhardt Brown (whose birth name was Erhardt Von Braun). He usually had a pet dog – in 1955, his dog was named Copernicus after Nicolaus Copernicus, the third in a line of pets named after famous scientists, and by 1985 his dog was named Einstein after Albert Einstein. Doc's role models were scientists, as evidenced by the names of his dogs and the portraits of Isaac Newton, Benjamin Franklin, Thomas Edison, and Albert Einstein found in his laboratory (which were on his fireplace mantle in 1955). Doc himself is a very positive person. He's always in crisis, he's always worried that he'll do something that might disrupt the space/time continuum, which would be a calamity for the entire universe. It weighs on his soul. So he constantly has to be one step ahead of himself — and he has a lot of fun doing it even though he gets himself in some nerve-wracking situations. He is a tall, lanky man standing 6'1" with wild, unkempt white hair (which changes color depending on the era), wide expressive brown eyes, and dramatic, animated facial expressions. Modeled after the "mad scientist" archetype like Albert Einstein, he features a hunched, energetic posture and iconic frantic gestures. He often uses the catchphrase “GREAT SCOTT” to express surprise, shock, fear or joy.