Mabel Loomis Todd or Mabel Loomis (November 10, 1856 – October 14, 1932) was an American editor and writer. She is remembered as the editor of posthumously published editions of Emily Dickinson and also wrote several novels and logs of her travel with her husband, astronomer David Peck Todd.
Todd’s relationship to the Dickinson family was complicated. She had a lengthy affair with Emily’s married older brother William Austin Dickinson. In preparing Emily’s poetry for publication, which was also marred by family controversies, she freely edited and adapted the writing to suit her own style.