Sinestro is a fascist, he wants order to the universe by wiping all that distant him out. Men, women, children. He wants to be feared by all...and he is feared by all.
~ Hal Jordan about Sinestro.
What should I do? Watch what the Guardians have made of there precious little universe? Scum! A thief here, a killer there! The universe is filled with unworthy life. The gnomes are doing nothing. They're weak! I'm not like that. In my world, there is no place for weakness!
~ Sinestro to Hal Jordan.
In blackest day, in brightest night, Beware your fears made into light, Let those who try to stop what's right, Burn like my power; Sinestro's might!
~ Sinestro reciting his Corps' oath
Thaal Sinestro, simply known as Sinestro, is a fictional character from DC Comics and the main antagonist of the Green Lantern franchise. He is one of the greatest and most powerful members of the Green Lantern Corps, leader of the "Sinestro Corps", and arch-nemesis of Hal Jordan, John Stewart, The Lantern Corps and the Guardians. Sinestro is the destructive master of a group of vicious Lanterns known as the "Sinestro Corps" in order to wipe out all Green Lantern's and bring a new order to the universe. He was created by John Broome and Gil Kane and first appeared in "Green Lantern Vol. 2 #7" (August 1961).
Thaal Sinestro, was born on the planet Korugar in Space Sector 1417. When he was young, he worked as an anthropologist, dedicated to restoring old ruins of long dead civilizations. One day, when Sinestro was working on one of the ruins, he saw a Green Lantern, crashed into the ruins. It was The Green Lantern known as Prohl Gosghota. The alien was mortally wounded and apperantly dying. He wished for Sinestro to call for help, and take his Power Ring, so he could heal himself. However Sinestro refused, and coldly took the ring and watched Phrohl Gosghota die a slow and painful death. So, Sinestro was made a galactic Green Lantern. Sinestro had become protector of Sector 1417, by The Guardians, the race of immortals that had formed The Green Lantern Corps to protect all life from the forces of evil.
Overtime Sinestro became the most respected Green Lantern, and the greatest to ever wield The Power Ring that was fueled by The Green Flame of Will. However, The Guardians soon learned that Sinestro had a dark side. Sinestro had become fixated on creating and maintaining his own twisted sense of "order", and wanted to rid the universe of scum and disobedience. The other Green Lantern's and The Guardians were also shocked by Sinestro's merciless and cruel tactics to get information. These included ruthless torture of criminals, and some necessary murder. The Guardians would often correct him of his own ruthlessness, but he would speak them out as fools.
When Abin-Sur died and his Power Ring was given to Earth test pilot Hal Jordan, the Guardians asked Sinestro to become his mentor and train the new recruit. From the beginning, Sinestro had little tolerance for his pupil and his tactics. While Hal considered all life sacred, including Earth's criminals, Sinestro fueled on wiping them from existence.
You will know the meaning of fear.
~ Sinestro in Injustice
Nothing frightens me. I am fear.
Sinestro in Super Friends
Sinestro in Superman: The Animated Series
Sinestro in Justice League
Sinestro with Giganta, Killer Frost, Parasite, Shade, and Clayface.