The protagonist of the series, a half-human, half-Gem hybrid. He is 13 at the start of the story and 16 in the finale. Male. He is characterized by a slightly chubby build, curly black hair, and a pink gemstone on his navel. Extremely kind and social, he is a staunch pacifist who seeks reconciliation even with enemies. He speaks in a bright, friendly manner. His weapons are a shield inherited from his mother and a protective pink bubble. He possesses healing abilities through his saliva. As he grows emotionally, his hidden powers awaken; by the end of the story and in 'Future,' he possesses the greatest strength among the Crystal Gems, capable of overwhelming and shattering even Jasper in a single blow.

The physical manifestation of the love between Ruby and Sapphire, fused together. Gender is unspecified (feminine-leaning). She is characterized by black afro hair, three eyes, a visor, and reddish-violet skin. Quiet and composed, she speaks in a cool, masculine-leaning, and concise manner. Her weapons are gauntlets on both fists. Possessing high future vision and overwhelming combat sense, her fighting strength is top-class within the team. The gap between her usual stoicism and the deep affection and smiles she occasionally shows her comrades is very endearing.

A former servant-class Gem who has lived for thousands of years. Her weapon is a spear. She boasts precise swordsmanship and agile movements, with high combat capability. She has a slender white-based build, a long face, and a pointed nose. Serious, methodical, and high-strung. She speaks in a polite and refined manner. She once held deep romantic feelings for her master, Rose Quartz, and is explicitly depicted as a lesbian character in the work.

A Gem born on Earth, thousands of years old. Her weapon is a whip. She is characterized by a short, plump build, purple skin, and long white hair. She has a rough, mischievous, and free-spirited personality. She speaks in a casual, boyish, and youthful tone. Her appearance is close to that of a human girl in her early teens. While her combat style is unrefined, she is strong in battle using tricky movements and shapeshifting abilities.

A ruthless elite warrior from Homeworld. Gender is unspecified (feminine-leaning). She is characterized by a large, muscular build, orange skin, and a striped pattern. She speaks in a bellicose and overbearing manner, looking down on the weak. Her weapon is a crash helmet on her head. Boasting high durability and charging power, she is extremely strong. While she despises fusion as a 'cheap tactic for weak Gems,' she burns with an intense obsession and rivalry toward Garnet's strength.

Gender unspecified (feminine-leaning). Originally a cold technician, her personality shifted to a comical and 'tsundere' type on Earth. She has a green body and triangular hair. Initially, she appeared tall because she wore robotic limb 'enhancers.' She speaks logically and formally. She has the ability to manipulate metal, but her pure combat strength is low.

A powerful Gem over several thousand years old who manipulates water. Her weapon is water wings manifested from her back. She possesses overwhelming strength, enough to lift all the Earth's oceans. She is characterized by blue skin, a bob cut, and a dress-like appearance. While she has a dark and suspicious personality, she opens her heart to Steven. She speaks quietly and with a certain lethargy. She was once sealed in a mirror and later sank to the ocean floor as the fusion 'Malachite' with Jasper. She chose this imprisonment (the cage of fusion) of her own will to suppress Jasper's violence and protect Steven.