Doctor of Letters (D.Litt., Litt.D., Latin: Litterarum Doctor or Doctor Litterarum) is a terminal degree in the humanities that, depending on the country, is a higher doctorate after the Doctor of Philosophy (Ph.D.) degree or equivalent to a higher doctorate, such as the Doctor of Science (Sc.D. or D.Sc.). It is awarded in many countries by universities and learned bodies in recognition of superior accomplishment in the humanities, original contributions to the creative or cultural arts, or scholarship and other merits. It may be conferred as an earned degree upon the completion of a regular doctoral course of study, usually including the development and defense of an original dissertation, or may be conferred as an earned higher doctorate after the submission and academic evaluation of a portfolio of sustained scholarship, publications, research, or other scientific work of the highest caliber.

In addition to being awarded as an earned degree, this doctorate is also widely conferred honoris causa to recognize one's lifetime of excellence in a particular humanistic, cultural, or artistic field, or other notable contributions to society. When conferred as an honorary doctorate, many or all of the standard degree requirements, including application, matriculation, coursework, doctoral dissertation or thesis, and portfolio evaluation may be waived, at the discretion of the degree-granting body. Honorary Doctor of Letters recipients do not necessarily have any previous affiliation with the awarding institution and, in most cases, it is not considered proper for them to use the title of "Dr." before their names. Universities, colleges, or learned bodies may award the honorary degree of Doctor of Letters, or the related Doctor of Humane Letters, to luminaries who have been identified as rare exemplars who have enriched the humanities in particular, or humanity at large. Mark Twain was awarded an honorary D.Litt. by Oxford University in 1907 for his literary contributions. Nelson Mandela was awarded honorary Doctor of Letters degrees by the University of Natal in 1993 and the Open University of Tanzania in 2000 for his leadership in the struggle against apartheid in South Africa.