Sinestro is one of the main DC Comics villains tied to Green Lantern, and in Lanterns he’s the former Green Lantern whose past with Hal Jordan makes him especially important. In the show, he is played by Ulrich Thomsen and is framed as a dangerous, highly intelligent figure whose history with the Corps still casts a long shadow.
Who he is
Thaal Sinestro first appeared in Green Lantern #7 in 1961 and was created by John Broome and Gil Kane. In the comics, he comes from Korugar and once served as a Green Lantern before being expelled for abusing his power and pursuing control over order rather than justice.
That makes him more than a random villain. He’s Hal Jordan’s classic nemesis, often described as Green Lantern’s equivalent to Lex Luthor or the Joker in other DC stories.
Why he matters in Lanterns
In Lanterns , Sinestro is not just a cameo or a name drop. The series uses him as a key part of Hal Jordan’s history, showing that Hal once had a close relationship with him before their paths split.
The show also leans into one of Sinestro’s best-known traits from the comics: he represents the corrupting side of fear. Green Lanterns draw power from will, while Sinestro is famously linked to fear and the yellow power that later became central to the Sinestro Corps.
Comics background
In the comics, Sinestro eventually goes beyond being a disgraced former Lantern. He becomes the founder of the Sinestro Corps, a force of yellow-ring wielders built around intimidation and fear.
That evolution is why the character has lasted so long. He can work as a mentor gone wrong, a political tyrant, or a cosmic threat, depending on the story.
In plain terms
If you’re asking who Sinestro is in Lanterns , the simplest answer is: he’s Hal Jordan’s old mentor-turned-enemy, and one of the most important villains in the Green Lantern mythos. His presence tells you the show is reaching deep into DC’s cosmic history, not just using a generic superhero bad guy.