Yes, it is Sir Walter Scott. Waverely, from 1814, sold about 40,000 copies; Guy Mannering sold about 50,000. His twenty-third bestselling novel (unidentified) sold about ten thousand copies. The twenty-fourth bestselling novel from this period — Fanny Burney’s Camilla — sold only four thousand. Scott was first also in the poetry market, with Byron a close second. Moore, Campbell, Rogers, and Southey dominate Coleridge and Wordsworth.
Keep all that in mind next time you despair about Dan Brown on the bestseller lists. More generally, we are leaving "winner-take-all" markets behind, not moving toward them.