Op den Graeff is a German and American family of Dutch origin. They were one of the first families of the Mennonite faith in Krefeld at the beginning of the 17th century. Various family members belonged to Original 13, the first organized immigration of a closed group of Germans to America in 1683. There the family had a long history in religious service and politics, beginning in the late 17th century in the Colony of Pennsylvania. In 1688, they became forerunners of the anti-slavery movement by signing the first anti-slavery protest in North America. Their descendants spread into various lines, Updegraff, Uptegraft, Updegraft, Updegrave, Updegrove, Uptegrove, Ubdegrove, Uptegraph, Upthagrove. The Updegraff branch of Ohio belonged to the leading families of the Quaker religious movement and produced a long line of ministers and elders.

Abraham Isaacs op den Graeff, also Op den Graff, Opdengraef as well as Op den Gräff was one of the so-called Original 13, the first closed group of German emigrants to North America, and an original founder of Germantown, Pennsylvania, as well as a civic leader, member of the Pennsylvania Provincial Assembly, award-winning weaver, and as an early abolitionist signer of the first organized religious protest against slavery in colonial America. He, or his brother Derick op den Graeff, are briefly mentioned in John Greenleaf Whittier's poem "The Pennsylvania Pilgrim" simply as "Op Den Graaf".