He is voiced by Phil LaMarr.
John Stewart was a US Marine Corp. During his time with the Marines, Stewart would meet the Green Lantern Corp. member Kama Tui, who had crashed there and would enlist John as a member of the Green Lanterns. John had grown-up reading comics passed on to him with his uncle, so the prospect of becoming a super-hero who was part of an alien defense-force appealed to John right away. Kama Tui had tried to teach John that his force-field could be shaped into anything, but John, a no-nonsense type soldier could not internalize the concept no matter how many times he recalled his training.
In the episode Secret Origins, John would return to Earth just in time to find it under attack by the alien threat, the Imperium. Superman and the Flash, would responde to the threat as would a newly discovered meta-human warrior woman named Diana, who would take on the nick-name Wonder Woman. The masked detective, Batman was already inside the ship and would help in the escape of J'onn Jones, the Martian Manhunter - a resident from Mars, the last world to fall victim to the Imperium. The Imperium moved from world to world, picking it clean. They had come to Earth when astronauts had stumbled onto the remnants of J'onn's civilization, with them inside. After the Imperium are defeated, the six decided to form a team, each had enough-power/skill to keep a moderate sized city safe, but together, they found they could save the whole world, or possibly worlds. John was glad to have tactical support so far from the Green Lantern home-planet of Oa. John would go on to mostly enforce daily regimens to keep the team focused. Though his exercises were to ridged to last for long, he continued to conduct himself with a similar disciplinary mind set.
During his training with the Corps, John fell in love with his trainer Katma Tui, whom he left when he returned to Earth. John entered into a relationship with Hawkgirl which came to a sudden end with the Thanagarian invasion. He would later form a relationship with fellow League member Vixen, which was complicated somewhat by the former Hawkgirl's return to active service with the League. A meeting with his and Shayera's future son, Warhawk, has done little to alleviate John's conflicted feelings. Carter Hall's interest in Shayera hasn't helped much, either. John eventually did rekindle his love for Hawkgirl, and they had a son together, Warhawk. This is explained in a graphic novel, Justice League Beyond, where on the night that John planned on proposing to Vixen, Shadow Thief impales her, and in a fit of rage, John murders him, leading to his expulsion from the Green Lantern Corps, and eventually to his marriage to Shayera.
John is often stoic but not humorless. He prefers to address threats with military precision, yet is not above causal humor or trivia talks with Flash. In the Green Lantern Corp. his ridged mind worked both for and against him. He took to the training well in that he had years of naval experience, however it had led to a distinct lack of creativity, which was invaluable for Green Lantern based on his powers.
Skills and Abilities
John's ring is Green Lantern Ring, all of which are empowered from the Green Lantern Battery on Oa, the power of which can be accessed a-far by the Green Lanterns' titular items. The Green Lantern power-source is kept on Earth to keep the planet safe, as such long space journey's tend to deplete the Ring. The Ring can create oxygen rich fields that transport the user and his allies through space at great speeds, but even at a moderate pace, the ring's power tends not to be able to last more than a day's journey. The force-field created by the ring can be shaped to look like anything, it can be made clear or solid green in it's form. The field is initially invulnerable, but if the force upon it is hard enough it disrupts the consciousness of the user keeping it up. Yellow objects can pierce the field as the green prism is a universally infused primordial power and the yellow is part of a competing primordial power that. Both colors surpass rings of their rival's power, making Yellow Lantern, Sinestro and John each-other's weakness.