Testator Definition:

One who has made a will; the author and signatory of a will.

Rapalje and Lawrence:

"Testator: a person who makes a will."

Similarly, Wharton (from the 1848 American imprint of the London edition):

"Testator: he who makes a will or testament."

A woman who has made a will can be called a testatrix.

REFERENCES:

• Rapalje, Stewart and Lawrence, Robert, A Dictionary of American and English Law, Volume II (Jersey City: Frederick D. Linn & Co. Law Publishers and Booksellers, 1883), page 1268.
• Wharton, John Jane Smith, Law Lexicon, or Dictionary of Jurisprudence: Explaining All the Technical Words and Phrases Employed in the Several Departments of English Law, including also the Various Legal Terms Used in Commercial Transactions; Together with an Explanatory as well as Literal Translation of the Latin Maxims Contained in the Writings of the Ancient and Modern Commentators (Harrisburg, Pennsylvania: M'Kinley and Lescure, 1848), page 1004.