8 passenger single engine low wing Cessna called?

An eight-passenger single-engine low-wing Cessna would be called a Pilatus PC-12. Cessna's low-wing singles are the Corvallis models, which are four-place planes. The biggest piston single they make is the Stationair, which only has six seats and it's high-wing. The Grand Caravan, which is an eight-place turboprop single, is also high-wing.

If you want an eight-place single you seem to have two choices: the Grand Caravan, which isn't low-wing, and the PC-12, which isn't a Cessna.