(1601 - 1671) Born to a gentry family, she was Cecil Calvert's cousin. She immigrated to Maryland in 1639, as a thirty-eight year old spinster, with her sister Mary (? - 1658) to join brothers Fulke (? - 1656) and Giles (1600 - ca. 1672), who were soon to be very influential in Maryland affairs. Margaret and Mary patented 'Sisters Freehold' near St. Mary's City upon arrival and soon became dominant and wealthy planters.
As Leonard Calvert's executrix, she administered his estate and performed essential government services at a crucial time for the colony. On 24 June 1648, she petitioned the assembly for a sear and two votes -- one as Calvert's agent and the second as a landowner -- but she was denied admission to the legislature, even though her male contemporaries praised her abilities. Often called the 'first suffragette,' Margaret removed to the Northern Neck of Virginia in the 1650s and established yet another large and thriving plantation, called 'Peace.' She died, unmarried, in 1671.