Cornelis Pietersz Bega, or Cornelis Pietersz Begijn (1631/1632 - 27 August 1664) was a Dutch Golden Age painter and engraver. Bega was born, lived and worked in Haarlem and was the son of sculptor and goldsmith Pieter Jansz. Begijn. His mother Maria was the illegitimate daughter of the Haarlem painter Cornelis van Haarlem. He assumed the name Bega when he started working professionally. He was a student of Adriaen van Ostade, and produced genre scenes of similar subjects, typically groups of a few peasant figures, often in interior settings, or fanciful figures such as The Alchemist (Malibu) or The Astrologer (London).