Cornelis is a Dutch form of the male given name Cornelius. Some common shortened versions of Cornelis in Dutch are Cees, Cor, Corné, Corneel, Crelis, Kees, Neel and Nelis.
Cornelis (Kees) and Johannes (Jan) used to be the most common given names in the Low Countries, and the origin of the term Yankee is commonly thought to derive from the term Jan-Kees for the Dutch settlers in New Netherland.
Some of the better known people named Cornelis were:
- Cornelis Engebrechtsz (c.1462-1527), painter from Leiden
- Cornelis Floris de Vriendt (1513/14-1575), architect and sculptor.
- Cornelis Cort (c.1533-1578), engraver and draughtsman
- Cornelis Corneliszoon (c.1550-1607), inventor of the wind powered sawmill
- Cornelis van Haarlem (1562-1638), leading Northern Mannerist painter
- Cornelis de Houtman (1565-1599), explorer who started the Dutch spice trade
- Cornelis Drebbel (1572-1633), builder of the first navigable submarine
- Cornelis de Vos (1584-1651), Flemish Baroque painter
- Cornelis de Graeff (1599-1664), Golden Age polician
- Cornelis Evertsen the Elder (1610-1666, 1628-1679, 1642-1706), three admirals in the Anglo-Dutch Wars
- Cornelis de Witt (1623-1672), politician of the Dutch Republic
- Cornelis Tromp (1629-1691), admiral in the Anglo-Dutch Wars and in the Scanian War
- Cornelis Pietersz Bega (1631/32-1664), painter and engraver
- Cornelis de Bruijn (1652-1726/27), artist and traveler
- Cornelis Cruys (1655-1727), first commander of the Russian Baltic Fleet
- Cornelis Dusart (1660-1704), genre painter, draftsman, and printmaker
- Cornelis M.H. (born 1953), governor of West Kalimantan, Indonesia
- Cornelis de Pauw (1739-1849), philosopher, geographer and diplomat
- Cornelis Tiele (1830-1902), theologian and scholar
- Cornelis Lely (1854-1929), civil engineer and statesman
- Cornelis Jacobus Langenhoven (1873-1932), South African writer and poet
- Cornelis Bernardus van Niel (1897-1985), microbiologist
- Cornelis Berkhouwer (1919-1992), President of the European Parliament 1973-75
- Cornelis van Beverloo (1922-2010), artist better known under his pseudonym "Corneille"
- Cornelis Vreeswijk (1937-1987), Dutch-Swedish singer, poet and actor