HMS Endeavour, also known as James Cook HMS endeavour, was a British Royal Navy research vessel that Lieutenant James Cook commanded to Australia and New Zealand on his first voyage of discovery from 1768 to 1771.

She was launched in 1764 as the collier Earl of Pembroke, with the Navy purchasing her in 1768 for a scientific mission to the Pacific Ocean and to explore the seas for the surmised Terra Australis Incognita or "unknown southern land". Commissioned as His Majesty's Bark Endeavour, she departed Plymouth in August 1768, rounded Cape Horn and reached Tahiti in time to observe the 1769 transit of Venus across the Sun. She then set sail into the largely uncharted ocean to the south, stopping at the islands of Huahine, Bora Bora, and Raiatea west of Tahiti to allow Cook to claim them for Great Britain. In September 1769, she anchored off New Zealand, becoming the first European vessel to reach the islands since Abel Tasman's Heemskerck 127 years earlier.

The ship was largely forgotten after her epic Pacific voyage, spending the next three years hauling troops and cargo to and from the Falkland Islands. She was renamed Lord Sandwich in 1775 after being sold into private hands, and used to transport timber from the Baltic. Rehired as a British troop transport during the American War of Independence, she was finally scuttled in a blockade of Narragansett Bay, Rhode Island in 1778. The wreck has not been precisely located but is thought to be one of a cluster of five in Newport Harbor.