The term traditionally applied to an individual of half-black and half-white heritage is mulatto, though that term is considered somewhat archaic, and even offensive, in some circles due to its origins. The term "mulatto" is rooted in the Spanish word for mule, which is half donkey and half horse.
In contemporary society, the term most often applied to people of black and white parentage is "mixed race" with or without a Latin distinction. Some people, however, prefer to be referred to as biracial. When in doubt, it is a good idea to simply ask people how they wish to be referenced in regard to their race or ethnicity.