Thaal Sinestro or Sinestro is an Alien from the planet Korugar in Green Lantern Sector 1417. He was considered one of the greatest living Green Lantern's and was the mentor to the first ever human Green Lantern and successor to his friend Abin Sur, Hal Jordan whom he mentored. During the Parallax crisis, Sinestro was instrumental in his defeat along with new recruit Hal Jordan on the planet Earth and Oa where the creature was defeated.