Claude Hopkins

American advertising executive — who created modern copywriting techniques, invented sampling and coupon advertising, wrote Scientific Advertising (1923) — earning $185,000 annually at his peak (extraordinary for the era) — whose methods defined advertising practice for decades.

Creates the scientific approach to advertising — Hopkins's core insight (that advertising is salesmanship in print and should be tested and measured rather than practiced as art) led to sampling programs, split testing, money-back guarantees, and accountable advertising — the foundations of direct response marketing.