Cas is a masculine given name and nickname, as well as a surname. Notable people with the name include:
Given name Cas Anvar (), Canadian actor, voice actor, and writer Cas Cremers (born 1974), Dutch computer scientist and professor of Information Security at the University of Oxford Cas Haley (born 1980), American singer-songwriter Cas Mudde (born 1967), Dutch political scientist Cas Oorthuys (1908–1975), Dutch photographer and designer known as Cas Cas Spijkers (1946–2011), Dutch chef and cookbook author Cas Walker (1902–1998), American businessman, politician, and television and radio personality Cas Wouters (1943–2025), Dutch sociologist nickname of James Castrission (born 1982), half of Cas and Jonesy, Australian explorers, endurance athletes and motivational speakers
Surname Katarina Čas (born 1976), Slovenian actress Marcel Cas (born 1972), Dutch former footballer
See also Cas Corach, a hero in Irish mythology Tál Cas, dynastic founder of the Dál gCais