Drill sergeant in Full Metal Jacket.
Not exactly a one-off or even first-time performance: R. Lee Ermey (who died almost exactly a year ago, age 74) had 61 acting credits in an acting career that spanned more than 30 years. He had in fact been a Marine sergeant, and had appeared in four films before Kubrick hired him as a military advisor on Full Metal Jacket. Kubrick was impressed enough to cast Ermey as Gunnery Sergeant Hartman, which became his break-out role. He was somewhat type-cast as drill sergeants after that, but according to IMDb, preferred comedy roles.
He was also (to me, anyway) the standout performance in a movie called Switchback, with Danny Glover and Dennis Quaid. Ermey plays a small-town lawman, and just embodies the role–in much the same way Tommy Lee Jones did in No Country For Old Men.