Cornelis Decker is a relatively little-known Dutch landscape painter who was active in Haarlem, where he was first recorded in 1643, entering the Guild of Painters. He may have been a pupil of Salomon van Ruysdael (1600/03-1670), but followed the school of Jacob van Ruysdael (1628-1682). He also imitated the style of Jan Wijnants (1632-1684) and Philips Wouwermans (1619-1668). Decker collaborated with Adriaen van Ostade (1610-1685), who sometimes painted the figures in his landscapes.
Decker is represented in the National Gallery, London; the Hackney Art Gallery, London; the Victoria and Albert Museum, London; the Louvre, Paris, amongst other collections.