Sir William Macgregor, 2nd Baronet (1817 – 29 March 1846) was a British Army officer.

The eldest son of the physician Sir Patrick Macgregor, 1st Baronet, he succeeded him in his baronetcy in 1828.^[1] On 20 March 1835, he purchased an ensigncy in the 18th Regiment of Foot.^[2] On 29 March 1839, he purchased a lieutenancy in the regiment.^[3]

Macgregor fought in the First Opium War, and fell ill from sunstroke at the Battle of Chinkiang.^[1] He was promoted captain shortly thereafter, on 22 July, to replace Captain Collinson, killed at the battle.^[4] He later returned to China overland before fully recovering from his sunstroke, to which cause his death was attributed.^[1] On 19 April 1844, he exchanged into the 92nd Regiment of Foot.^[5]

Macgregor died at Gibraltar in 1846.^[1] He was attended by his brother-in-law, the Rev. Joseph Sortain.^[6]