As a general rule, surnames are derived from (1) a father's name, (2) family's place of dwelling, (3) occupation, or (4) nicknames or attribute. (See web brief on surnames or 1857 essay for examples.) A Crowther was one who played a crowth, probably as an occupation. The crowth was the english precursor to the modern harp and fiddle (google 'crowth' for more info) and what the welsh knew as the crowth the scandinavians called a crwth, the irish called a cruit, and the old english called a croud, a croude, a crowd, or a crouth. (One never knows how things are spelled when so many were illiterate.)

According to the earliest Crowthers were known in Yorkshire by the names Katerina Crowder and Thomas Crouder were recorded as holding estates in the year 1379 (Yorkshire is in England - hence the spelling) and some of the first US settlers of this name were John Crowther, who settled in New Hampshire in 1631, Elizabeth James and Mary Crowthers, who settled in Richmond, Virginia in 1820, and Thomas Crowder who settled in Barbados in 1634 and later transferred to the mainland. (source and crest)