Regnier de Graaf, Dutch physician and anatomist (died 1673)

Regnier de Graaf, original Dutch spelling Reinier de Graaf, or Latinized Reijnerus de Graeff, was a Dutch physician, physiologist and anatomist who made key discoveries in reproductive biology. He specialized in iatrochemistry and iatrogenesis, and was the first to develop a syringe to inject dye into human reproductive organs so that he could understand their structure and function.