What term describes a person who has left a will upon their death?

The term that describes a person who has left a will upon their death is "testate." This term derives from the Latin word "testamentum," which refers to a will. A testate individual has specified their wishes regarding the distribution of their assets and other matters in a legal document, ensuring that their estate is settled according to their intentions.

In contrast, the term "intestate" refers to someone who dies without having made a will. An executor is a person appointed to carry out the instructions of a will but does not define whether or not a will exists. Lastly, a beneficiary is someone who receives assets or benefits from a will but does not indicate whether the deceased had a will at all. Thus, "testate" is correctly associated with having left a will upon death.