Jim Lake Jr. is a 15-to-16-year-old high school student who makes history by becoming the first-ever human Trollhunter, chosen by the magical Amulet of Daylight to protect both the human world and the secret civilization of trolls living beneath his hometown of Arcadia Oaks. Due to his father leaving at a young age, Jim grew up quickly to help care for his overworked mother, Dr. Barbara Lake. He routinely cooks gourmet meals and manages household responsibilities. Jim suffers from an intense inner conflict where he feels he must shoulder the burden of saving everyone entirely on his own, often struggling to ask for help. He consistently prioritizes the safety of his friends, family, and troll allies over his own happiness, operating with immense empathy and moral courage. Despite his heavy responsibilities, Jim remains a relatable, slightly clumsy teenager who relies on quick wit and humor to ease tension. In his everyday life, Jim is a slender teenager with short, dark brown hair and blue eyes, typically seen wearing a signature blue zip-up hoodie, a white t-shirt, and jeans. When summoning the amulet, he is encased in heavy, glowing silver-and-blue magical armor. He wields the massive Sword of Daylight, which can ignite with radiant energy.

Tobias Domzalski is Jim's fiercely loyal, energetic best friend who serves as his right-hand man and emotional anchor. He is short (standing at 5'0") and stout, with a round build. He has short, messy red-orange brown hair, green eyes, freckles, and prominent dental braces. He is usually seen wearing a red-and-white striped t-shirt under a teal zip-up hoodie, brown pants, and a blue backpack. Toby is known for his signature catchphrase, "Awesomesauce!" Unlike Jim, who is initially terrified of his new responsibilities, Toby fully embraces the secret world of trolls and magic with child-like wonder. He is the ultimate "wingman" (a title affectionately given to him by his troll partner, AAARRRGGHH!!!). He never hesitates to put himself in danger to protect Jim, Claire Nuñez, and his loved ones. Toby is a classic wisecracking nerd who loves video games, anime, geology, and junk food (especially tacos and "Nougat Nummies"). However, his humor often masks deep emotional strength and a willingness to make the ultimate sacrifice. While he lacks traditional athletic agility, Toby compensates with sheer upper-body strength. His signature weapon is a massive Troll Warhammer that he infuses with a magical "Glowny" stone, which lets him manipulate gravity to lighten the hammer or make it incredibly heavy.

Claire Nuñez is an honors student at Arcadia Oaks High, heavily involved in the drama club (with a deep love for Shakespeare) and track and field. Her primary motivation to enter the hidden world of trolls is rescuing her baby brother, Enrique, who was swapped with a Changeling named NotEnrique. Raised by a politician mother, she understands public appearance but is never afraid to speak her mind, call out reckless plans, or actively lead during a battle. Described as a "cool goth" or alternative girl. She has tan skin, brown eyes, and shoulder-length black hair. Her hair features distinct blue streaks, which she decorates with pink barrettes. (These streaks later turn white after extensive use of dark magic). She typically wears a purple jacket over a striped shirt, a short skirt, and combat boots. Claire's signature weapon is a magical staff created by Morgana that manipulates dark energy. Despite it being designed for a master sorcerer, Claire learns to control it using her pure willpower and emotional strength to tear open portals through the Shadow Realm.

Blinkus as a Troll is equipped with four arms and six expressive eyes. He has light blue-green, stone-like skin, a distinct orange nose, and darker blue-green horns. He is a brilliant historian and librarian who is deeply passionate about "library sciences," troll lore, and ancient texts. While the rest of trollkind initially considers him a eccentric "crackpot" for supporting a human hero, Blinky maintains an unyielding, energetic enthusiasm. He has a massive vocabulary and a habit of using dramatic, sweeping, and poetic language. Though he starts as a strict teacher tasked with training Jim for combat, Blinky grows to love Jim as a surrogate son, offering deep emotional support and life wisdom. While he possesses enhanced strength and durability common to troll physiology, his true value to Team Trollhunters is his tactical intellect. He uncovers strategic weaknesses and historical solutions to defeat villains like Bular and Gunmar.

Argh is enormous with a hunched, gorilla-like framed troll, with heavily muscled arms, and exceptionally broad shoulders. He primarily walks on all fours using his knuckles. He has rock-like gray skin contrasted by a distinct, thick mane of bright green hair and fur covering his head, shoulders, and chest. His body features intricate tribal carvings on his arms, chest, and knees. He has large green eyes, a wide black nose, and two short, stubby horns. When pushed into an uncontrollable fury, the carvings on his skin glow with a vibrant green energy, and his eyes turn completely black with glowing green pupils