Scar is the nickname for a Raider fighter ace. The nickname is derived from battle damage on the Raider's fuselage that resembles a scar. The nickname blends logically since Raiders have been discovered as a biomechanical creation of the Cylons which is bred for space battle.
Scar is responsible for many ruthless, successful attacks against the Fleet. The need to eliminate Scar's threat increases a pilot rivalry between Captain Kara Thrace and Lieutenant Louanne Katraine.
Scar was later destroyed on the 29th day of mining operations. Starbuck engaged him, but broke off a suicide run against him in favor of luring him into the sights of her wingman, Kat. Scar was then destroyed by Kat. (Scar).
Notes
This storyline of destroying an enemy fighter ace may be derived from the Royal Air Force's hunt for Manfred von Richthofen (a.k.a. the "Red Baron") during WWI.