James Alexander Henderson was the proprietor of the Belfast News Letter, the oldest newspaper in the entire English-speaking world.

He was born in Newry in 1822 and was the son of James Henderson, proprietor of the Newry Telegraph. Henderson took over management of paper on 1 April 1845, following the death of his father-in-law, Alexander Mackay.

Under Henderson’s direction the number of editions was increased from two to three, with papers distributed on Monday, Wednesday and Friday. In 1855 the News Letter was published daily. Henderson was President of the Newspapers Society and a founder of the Press Association.

In addition to his two terms as Mayor, Henderson also served as alderman and Justice of the Peace. He was made a Magistrate of the Borough of Belfast during the first Viceroyalty of the Duke of Abercorn. Henderson sat on the Committee of the Belfast Charitable Society, served as a member of the Belfast Board of Guardians and was a member of the Harbour Board.

Henderson died on 8 April 1883 aged sixty.