Major William Rainsborowe, or Rainborowe, was an officer in the English Navy and New Model Army in England during the English Civil War and the Interregnum. He was a political and religious radical who prospered during the years of the Parliamentary ascendancy and was an early settler of New England in North America.

Thomas Rainsborough, or Rainborowe, 6 July 1610 to 29 October 1648, was an English religious and political radical who served in the Parliamentarian navy and New Model Army during the Wars of the Three Kingdoms. One of the few contemporaries whose personal charisma and popularity rivalled that of Oliver Cromwell, he has also been described as "a soldier of impressive professional competence and peerless courage".