Zachariah Gillam (also spelled Zachary Guillam) (1636–1682) was one of a family of New England sea captains involved in the early days of the Hudson's Bay Company.
In 1668, in command of the 43-ton Nonsuch he carried Groseilliers from England to Hudson Bay where they wintered at the mouth of the Rupert River and returned the following year with £1,300 in furs.
In May 1670, the same month that the Hudson's Bay Company was founded, he left England in the 75½-ton Prince Rupert[2] with Groseilliers accompanied by Wivenhoe with Radisson and the new governor Charles Bayly.
He was engaged in the coastal trade to North Carolina from 1677 to 1680 when he was accused of involvement in the 1677 Culpeper's Rebellion and sent in custody to England.
His elder brother Benjamin Gillam was in 1665 in command of Charles which brought Radisson and Groseilliers to England where they began the foundation of the Hudson's Bay Company.