John Fergus (c. 1796 – 23 January 1865) was a British Whig politician. Fergus was first elected Whig MP for Kirkcaldy Burghs at the 1835 general election and held the seat until 1837 when he did not seek re-election. He returned to parliament as an MP for Fife in 1847, holding the seat until 1859, when he retired.