John Putnam Demos (born 1937) is an American author and historian. He has written two books about witch hunts and has discovered that one of his ancestors was John Putnam Senior, a member of the Putnam family that was prominent in the Salem witch trials.
John Putnam Demos was born in 1937 in Cambridge, Massachusetts to the Greek-American philosopher Raphael Demos.
He graduated from Harvard University.
Demos was awarded the prestigious Bancroft Prize for his book Entertaining Satan. He was awarded the 1995 Francis Parkman Prize for his book The Unredeemed Captive: A Family Story From Early America.
He retired in December 2008 as the Samuel Knight Professor of History at Yale University.
Demos lives in Tyringham, Massachusetts.