Cecil Calvert, 2nd Baron Baltimore (8 August 1605 – 30 November 1675) was an English politician and lawyer who was the first proprietor of Maryland. Born in Kent, England in 1605, he inherited the proprietorship of overseas colonies in Avalon (Newfoundland) along with Maryland after the 1632 death of his father, George Calvert, 1st Baron Baltimore (1580–1632), for whom it had been originally intended in a vast land grant from King Charles I (1600–1649, reigned 1625–1649). Young Calvert proceeded to establish and manage the Province of Maryland as a proprietary colony for English Catholics from his English country house of Kiplin Hall in North Yorkshire.

As a Catholic, he continued his father's legacy by promoting religious tolerance in the colony. He also was involved in the establishment of the Newfoundland Colony and the Province of Avalon. Maryland quickly became a haven for English Catholics in the Americas, particularly due to rising religious persecution in England. Governing Maryland's affairs since its founding for 44 years, Calvert died in England in 1675. After his death, the Protestant Revolution along the Chesapeake Bay ("Glorious Revolution") of 1689, matched events occurring overseas across the Atlantic Ocean in Europe, overturning King James II and the Stuart royal dynasty of England and Scotland, and ended Roman Catholic control (and temporarily that of the Calvert family and the Lords Baltimore) of the Province of Maryland colony (including the other original Thirteen Colonies along the East Coast of British America), and established Protestant supremacy.

Calvert was born on 8 August 1605 in Kent, England, to George Calvert, a young English lawyer and assistant to Lord Cecil (1563–1612), Secretary of State to King James I, and was christened "Cecilius" in honour of his father's employer. His mother, his father's wife, was Anne Mynne (or Mayne), and he was the first of several sons. At the time, his father was under pressure to conform, and all ten children were baptised into the Church of England.

Calvert entered Trinity College, Oxford, in 1621. His mother died the following year. In 1625, his father, George Calvert, was created the first Baron Baltimore, of Baltimore, County Longford, in the peerage of Ireland, which did not give him a seat in the English House of Lords. He formally converted to Roman Catholicism the same year, and it is likely that his children followed him; at least his sons did.^{[citation needed]}

In 1628, Cecil Calvert accompanied his father, along with most of his siblings and his stepmother, to the newly settled Colony of Newfoundland. The colony failed due to disease, extreme cold and attacks by the French, and the family returned to England.^{[citation needed]}

Cecil Calvert succeeded as the second Baron Baltimore upon his father's death in April 1632. On 8 August 1633, the new Lord Baltimore was called to the bar as a barrister from Gray's Inn.

Lord Baltimore, as Cecil now was, received a Charter from King Charles I for the new colony of Maryland, to be named for the Queen Consort, Henrietta Maria (wife of King Charles I). This was shortly after the death, in April 1632, of his father, George who had long sought the charter to found a colony in the mid-Atlantic area to serve as a refuge for English Roman Catholics. The original grant would have included the western shore of the Chesapeake Bay as far south as the Potomac River and the entirety of the eastern shore (later known as the Delmarva peninsula).^{[citation needed]}

When the Crown realised that settlers from Virginia had already crossed the bay to begin settling the southern tip of their eastern shore, the grant was revised to include the eastern shore only as far south as a line drawn east from the mouth of the Potomac River (including the future State of Delaware). Once that alteration was made, the final charter was confirmed on 20 June 1632. This charter would be heavily contested by the 2nd Lord Baltimore's heirs and the Penn family in the Penn–Calvert Boundary Dispute.