The Sinestro Corps is an organization of villains in the DC Universe and are primarily enemies of the Green Lantern Corps. Their rings are moved to impose fear on others, with them being able to make constructs that look like the opponent's worst fear.
In other Media[]
The team only appears in video games like DC Universe Online and Lego Batman 3 (where Arkillo was a member of the group), in the cartoon Green Lantern the group was alluded to by yellow crystals that caused fear.