McCahill is a surname of Irish origin. The name refers to:

• Crystal McCahill (born 1983), Playboy Playmate of the month May 2009
• Jim McCahill (born 1939), English football chairman
• Mark P. McCahill (born 1956), American developer of internet technology
• Romy McCahill (born 1993), Scottish model and beauty pageant titleholder
• Tom McCahill (1907–1975), American automotive journalist

• Cahill (disambiguation)