A titled Englishman born and raised in New York, an unsettlingly deadpan interview subject capable of passionate and frenetic onscreen portrayals, a successful screenwriter and director who does his best work by allowing his actors to improvise every scene, and seemingly average by all outward appearances despite these at once contradictory and complementary aspects, Christopher Guest has had a long and varied career, achieving cult status for work in such unforgettable pseudo-documentaries as "This is Spinal Tap" (1984) and "Waiting For Guffman" (1997). The son of a British peer (Guest