Doris "Granny D" Haddock (born Ethel Doris Rollins; January 24, 1910 – March 9, 2010) was an American political activist from New Hampshire. Haddock achieved national fame when, between the ages of 88 and 90, starting on January 1, 1999, and culminating on February 29, 2000, she walked over 3,200 miles (5,100 km) across the continental United States to advocate for campaign finance reform. In 2004, she ran unsuccessfully as a Democratic challenger to incumbent Republican Judd Gregg in the U.S. Senate election in New Hampshire.

Haddock's walk across the country followed a southern route and took more than a year to complete, starting on January 1, 1999, in southern California and ending in Washington, D.C., on February 29, 2000.

Haddock requested a name change of her middle name to "Granny D", the name by which she had long been known. On August 19, 2004, Haddock's request was officially granted by Judge John Maher during a hearing at the Cheshire County probate court.