Mary Matilda Betham, known by family and friends as Matilda Betham (16 November 1776 – 30 September 1852), was an English diarist, poet, woman of letters, and miniature portrait painter. She exhibited paintings at the Royal Academy of Arts from 1804 to 1816. Her first of four books of verses was published in 1797. For six years, she researched notable historical women around the world and published A Biographical Dictionary of the Celebrated Women of Every Age and Country in 1804.