John Collier Underhay (15 January 1829 – 23 October 1919) was a farmer, land surveyor and political figure in Prince Edward Island. He represented 1st Kings from 1879 to 1882 and 2nd Kings from 1886 to 1893 in the Legislative Assembly of Prince Edward Island as a Liberal and then a Conservative member. Underhay was an unsuccessful candidate for a seat in the province's legislative council in 1874 and was defeated when he ran for reelection in 1882.