Sewall is a surname. Notable people with the surname include:
Arthur Sewall (1835–1900), American Democratic politician from Maine
Charles S. Sewall (1779–1848), American politician
George P. Sewall (1811–1881), American lawyer and State Representative from Old Town, Maine
Gilbert T. Sewall (born 1946), American educator and author
Harold M. Sewall (1860–1924), American politician and diplomat
Harriet Winslow Sewall (1819–1889), American poet
Jonathan Sewall (1729–1796), last British attorney general of Massachusetts
Joseph Sewall (1921–2011), American politician and Senator from Maine
May Wright Sewall (1844–1920), American feminist, educator, and lecturer
Richard B. Sewall (1908–2003), American professor of English at Yale University
Samuel Sewall (1652–1730), American judge in Massachusetts
Samuel Sewall (congressman) (1757–1814), American lawyer and congressman
Sarah Sewall, American lecturer at Harvard Kennedy School
Stephen Sewall (academic) (1734–1804), American professor at Harvard University
Sumner Sewall (1897–1965), American Republican politician and airline executive
Thomas Sewall (1786–1845), American physician