Thomas Delavall was a London-born opportunist, businessman, and official of the early English colonial period. Tradition holds that he came to America in 1664 as an officer in the English army commanded by Richard Nicolls.

Often called "Captain," Delavall was appointed receiver-general of New York colony in 1664, mayor of New York City in 1665 and again in 1673, member of the governor's council of advisors in 1667, and commissary or judge of the province in 1679.

Although primarily Manhattan based, Delavall acquired extensive real estate across the colony. He owned a house in New York City and in Kingston, a mill at Yonkers, land at Gravesend, and other property in southern New York.

In 1668, he was in Albany on behalf of the provincial governor - probably in a military capacity. In 1670, Governor Francis Lovelace granted him permission to build a house on the hill in Albany. Albany leaders resented the encroachments of well-connected outsiders and taxed Delavall's property to the maximum. But in that year, he was appointed an Albany magistrate and attended the Albany court on many occasions.

In 1673, his property was confiscated by the Dutch when they re-took the province. Pre-occupied elsewhere, he spent little time in Albany after the return of the Duke's government in 1674. However, in 1679, he still was listed on a census of Albany householders.

During the latter part of the 1670s, Sheriff Richard Pretty was his protege. Delavall liquidated his Albany holdings in 1679. In 1680, he empowered Marte Crieger, Jr. to act on his behalf in the Albany area. His son, John, and his daughters' husbands succeeded him in most of his New York endeavors.

During the 1670s, Delavall travelled to England.