Blay is a surname. Notable people with the surname include:
- Andre Blay (1937–2018), American businessman, film producer and studio executive
- Eddie Blay (1937–2006), Ghanaian boxer
- Eva Alterman Blay (born 1937), Brazilian sociologist and politician
- Freddie Blay (born 1942), Ghanaian lawyer and politician
- George Blay (born 1980), Ghanaian footballer
- J. Benibengor Blay (born 1915), Ghanaian journalist, writer, publisher and politician
- Pep Blay (born 1966), Catalan writer, script writer and music journalist
- Ruth Blay (died 1768), last woman executed in New Hampshire
- Robert Samuel Blay (1901-1979), Ghanaian judge
- Philippe Blay (born 1960), French musicologist