Guilt
Guilt was a feeling of self-consciousness in which one experienced a sense of distress about an individual's potential responsibility for a negative outcome.
In 2287, Leonard McCoy claimed that Sybok took away his pain, but James T. Kirk noted that as McCoy was a doctor, he knew that pain and guilt couldn't be taken away with the wave of a magic wand. (Star Trek V: The Final Frontier)
In 2374, Captain Benjamin Sisko reflected in a later deleted personal log that a guilty conscience was a small price to pay for the safety of the Alpha Quadrant, regarding the morally dubious actions he had taken to bring the Romulan Star Empire into the Dominion War against the Dominion. (DS9: "In the Pale Moonlight")