The surname Sewall, or more correctly, Sewell, is presumably Anglo-Saxon and comes from Coventry, England in the generations before migration in 1634 to Newbury, Massachusetts.
Henry Sewell returned to England during the Commonwealth, but returned to America after the restoration. His son, Judge Samuel Sewall (1652-1729) ,was born in England, died in Boston.He presided at the Salem witchraft trials for which he later apologized. His brother, John, settled in York, Maine and has numerous descendants. A cousin, also Henry, migated to Maryland and is the ancestor of the southern branch. During the American Revolution, Jonathan Sewell, the Attorney General of Massachusetts, was a loyalist and fled to Halifax. He became attorney general of Quebec and left numerous descendants who changed the spelling back to Sewell. The Canadian Sewells organized a reunion several years ago in Quebec which about a dozen American Sewalls including me and my son, Henry sewall Wright, attended. My great-grandfather, Joseph Sewall (1827-1917) migrated west to Minnesota for his health.
My Y-DNA haplogoup is E-L542, as determined by Family Tree DNA. David T. Sewall, Orono, Maine, direct descendant of Henry Sewall (or possibly Sewell), of Coventry, England. This haplogroup is most commonly found today in the Balkans, which suggests the possibility that an early Sewall/Sewell ancestor arrived in England as a soldier with the Roman Army during the Roman Conquest of Britain. (David T. Sewall)