Hal (Ryan Reynolds)
In a universe as vast as it is mysterious, an elite, powerful force has existed for centuries. Protectors of peace and justice, they are called the Green Lantern Corps. Warriors sworn to keep intergalactic order, each Green Lantern wears a ring that grants him the ability to create anything his mind can imagine. But when a new enemy called Parallax threatens to destroy the balance of power in the Universe, their fate and the fate of Earth lie in the hands of their newest recruit, the first human ever selected: Hal Jordan.
Hal is a gifted and cocky test pilot, but the Green Lanterns have little respect for humans, who have never harnessed the infinite powers of the ring before.
Carol (Blake Lively)
But Hal’s humanity is one weapon no member of the Corps has ever had, and if—with willpower, determination and the encouragement of fellow pilot and childhood sweetheart Carol Ferris —Hal can quickly master his new powers and find the courage to overcome his fears, he may prove to be not only the key to defeating Parallax…he will save the Earth and all of mankind from certain destruction.
Sinestro (Mark Strong)
Hal has a different kind of adversary in Thaal Sinestro, the leader of the Green Lantern Corps, who mourns the loss of fallen Lantern Abin Sur as strongly as he questions the choice of Hal to take his place; although, according to everything he knows, the ring never makes a mistake.
Hector (Peter Sarsgaard)
The third-wheel in Hal and Carol’s longstanding on-again, off-again relationship is Hector Hammond. Hector grew up with them and was a friend, but was always on the outside looking in, having both a desire for Carol and a desire to be Hal. Brilliant but forever failing to meet the unrealistic expectations of his father, he has become a professor at a community college, whose specialty is even more obscure than he is: xenobiology.
Hal’s power rests in his ring. Several ideas were worked through for the Green Lantern power ring, which also incorporated the prism motif. Each one was tried on Ryan Reynolds’ hand, to ensure that the size and shape and fit were just so. The actor’s opinion was important as they wanted him, like Hal, to feel powerful wearing it, as though he could wield the ring as a weapon.
After coming into contact with Parallax, Hector begins to develop powers of his own. Just as Hal’s will is empowered by the color green, Hector’s eyes glow yellow as he draws strength from the fear of others. Always viewing Hal as a rival and Carol as unattainable, Hector’s newfound confidence begins to bring the worst out in him.
The character of Hal goes back over 70 years, first appearing in All-American Comics in 1940, and evolving over time. The Green Lantern Corps is a federation assigned to police the 3,600 sectors in the universe, overseen by an ancient race of immortals called the Guardians, who reside on the planet Oa.