Merrill Markoe (born 1951) is an author, a television writer and a sometime standup comedienne. She graduated from the University of California, Berkeley. She has written for many television shows, among them the failed 1977 revival of Laugh In, Newhart, Sex and the City and Moonlighting, but she may be best known for her work on Late Night with David Letterman (a show for which she won five Emmys). She was the show's original head writer, and was the head writer on Letterman's short-lived live NBC morning show in 1980. She engineered most of the original concepts and architecture for the ground-breaking late night talk show, along the way creating the segment "Stupid Pet Tricks," as well as "Stupid Human Tricks" and "Viewer Mail." Many of the ideas behind the remote segments outside the studio came from Markoe, who also won a Writer's Guild award for her writing/performing work on HBO's late-1980s hit Not Necessarily the News. She and Letterman were also involved romantically throughout the 1980s, but by 1988 they had broken up and Markoe moved to California to pursue a writing career.

She went on to do on-camera writer work as a lifestyle reporter at KCOP-TV in Los Angeles, then for Michael Moore's short lived NBC show T.V. Nation, as well as other magazine shows such as Lifetime magazine. In the early 90s she wrote and directed a number of HBO and Cinemax comedy specials.

In 2005 she was a regular panelist on Animal Planet's Who Gets the Dog? She has had a number of columns and written for many periodicals including Rolling Stone, Time, New York Woman, New Woman, US News and World Report, US, People, Esquire, The Huffington Post, Glamour, The New York Times, The Los Angeles Times, LA Weekly, Real Simple, etc. She appears in episode 2 of Friends as Marsha, the irritable museum curator and can be seen in the movie EDTV as a panelist, as well as in the cast of The Aristocrats. She appeared in two episodes of Space Ghost Coast to Coast from 1996-1997 as the unwilling subject of the Late Night talk show host's affections. Her books include Merrill Markoe's Guide to Love, How To Be Hap-Hap-Happy Like Me, What the Dogs Have Taught Me, It's My F ing Birthday, The Psycho Ex Game (cowritten with Andy Prieboy) and Walking in Circles Before Lying Down.