Major Robert Ross (c.1740 – 9 June 1794) was the officer in charge of the First Fleet garrison of marines, and Lieutenant-Governor of the convict settlement of Norfolk Island.
Ross was born in Scotland, and joined the marines in June 1756, being present at the siege of Louisburg and the capture of Quebec during the Seven Years' War (1756–63). Promoted to captain, he saw action at Bunker Hill in June 1775 during the American War of Independence. He was aboard HMS Ardent in August 1779 when it was captured and he was taken prisoner by the French.
In 1786 he volunteered for the newly formed New South Wales Marine Corps and was designated its commander with the brevet rank of major. Accompanied by his eight-year-old son, he sailed to New South Wales on HMS Sirius, transferring to Scarborough during the voyage.
From the start of his time in New South Wales Ross was in conflict with the governor Arthur Phillip and other officers. David Collins claimed an “inexpressible hatred” for him, and Ralph Clark described him at the time as “without exception the most disagreeable commanding officer I ever knew”. He refused to allow the marines to supervise the convicts at work, or to allow marine officers to sit as members of the criminal court, attitudes which some of his own officers disagreed with. He criticised Phillip for not building fortifications, and missed no opportunity to embarrass and hinder the governor. His actions made Phillip's task of administering the fledgling colony more difficult.