Tobias Furneaux (August 21, 1735 - September 19, 1781) was an English navigator and Royal Navy officer, who accompanied Captain James Cook on his second voyage of exploration.

Furneaux was born at Swilly near Plymouth. He entered the Royal Navy, and was employed on the French and African coasts and in the West Indies during the latter part of the Seven Years War (1760-1763). He served as second lieutenant of the Dolphin under Captain Samuel Wallis on the latter's voyage round the globe (August 1766 - May 1768). Furneaux was made a commander in November 1771, and commanded the Adventure which accompanied Captain Cook (in the Resolution) on Cook's second voyage.

On this expedition Furneaux was twice separated from his leader (February 8 - May 19, 1773; October 22, 1773 - July 14, 1774, the date of his return to England). On the former occasion he explored a great part of the south and east coasts of Tasmania, and made the earliest British chart of the same. Most of his names here survive; Cook, visiting this shore-line on his third voyage, confirmed Furneaux's account and delineation of it (with certain minor criticisms and emendations), and named after him the islands in Banks Straits , opening into Bass's Straits, and the group now known as the Low Archipelago.

After the Adventure was finally separated from the Resolution off New Zealand in October 1773, Furneaux returned home alone, bringing with him Omai of Ulaietea . This first South Sea Islander seen in the British Isles returned to his home with Cook in 1776-1777.

Furneaux was made a captain in 1775. During the American Revolution, he commanded the Syren in the British attack of the 28th of June 1776 upon Charleston, South Carolina.