Family name Issaac (Issaac 
) , in all the world, is a rare cognomen. The last name Issaac is habitual in the Dominican Republic, where it is a rare surname, Nigeria, where it is a very rare surname, and Honduras. In absolute terms, it is commonest in Nigeria, the Dominican Republic, and the United States. More frequently, Issaac is the forename as well as the last name.